Wood surface, showing several features

Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers (which are strong in tension) embedded in a matrix of lignin which resists compression. Wood is sometimes defined as only the secondary xylem in the stems of trees,^[1] or it is defined more broadly to include the same type of tissue elsewhere such as in tree roots or in other plants such as shrubs.^{[citation needed]} In a living tree it performs a support function, enabling woody plants to grow large or to stand up for themselves. It also mediates the transfer of water and nutrients to the leaves and other growing tissues. Wood may also refer to other plant materials with comparable properties, and to material engineered from wood, or wood chips or fiber.

The earth contains about one trillion tonnes of wood, which grows at a rate of 10 billion tonnes per year. As an abundant, carbon-neutral renewable resource, woody materials have been of intense interest as a source of renewable energy. In 1991, approximately 3.5 billion cubic meters of wood were harvested. Dominant uses were for furniture and building construction.^[2]

History[link]

A 2011 discovery in the Canadian province of New Brunswick uncovered the earliest known plants to have grown wood, approximately 395 to 400 million years ago.^[3]

People have used wood for millennia for many purposes, primarily as a fuel or as a construction material for making houses, tools, weapons, furniture, packaging, artworks, and paper.

Wood can be dated by carbon dating and in some species by dendrochronology to make inferences about when a wooden object was created.

The year-to-year variation in tree-ring widths and isotopic abundances gives clues to the prevailing climate at that time.^[4]

Physical properties[link]

Growth rings[link]

Wood, in the strict sense, is yielded by trees, which increase in diameter by the formation, between the existing wood and the inner bark, of new woody layers which envelop the entire stem, living branches, and roots. This process is known as secondary growth; it is the result of cell division in the vascular cambium, a lateral meristem, and subsequent expansion of the new cells. Where there are clear seasons, growth can occur in a discrete annual or seasonal pattern, leading to growth rings; these can usually be most clearly seen on the end of a log, but are also visible on the other surfaces. If these seasons are annual these growth rings are referred to as annual rings. Where there is no seasonal difference growth rings are likely to be indistinct or absent.

If there are differences within a growth ring, then the part of a growth ring nearest the center of the tree, and formed early in the growing season when growth is rapid, is usually composed of wider elements. It is usually lighter in color than that near the outer portion of the ring, and is known as earlywood or springwood. The outer portion formed later in the season is then known as the latewood or summerwood.^[5] However, there are major differences, depending on the kind of wood (see below).

Knots[link]

A knot on a tree at the Garden of the Gods public park in Colorado Springs, Colorado (October 2006)

A knot is a particular type of imperfection in a piece of wood; it will affect the technical properties of the wood, usually for the worse, but may be exploited for visual effect. In a longitudinally sawn plank, a knot will appear as a roughly circular "solid" (usually darker) piece of wood around which the grain of the rest of the wood "flows" (parts and rejoins). Within a knot, the direction of the wood (grain direction) is up to 90 degrees different from the grain direction of the regular wood.

In the tree a knot is either the base of a side branch or a dormant bud. A knot (when the base of a side branch) is conical in shape (hence the roughly circular cross-section) with the inner tip at the point in stem diameter at which the plant's vascular cambium was located when the branch formed as a bud.

During the development of a tree, the lower limbs often die, but may remain attached for a time, sometimes years. Subsequent layers of growth of the attaching stem are no longer intimately joined with the dead limb, but are grown around it. Hence, dead branches produce knots which are not attached, and likely to drop out after the tree has been sawn into boards.

In grading lumber and structural timber, knots are classified according to their form, size, soundness, and the firmness with which they are held in place. This firmness is affected by, among other factors, the length of time for which the branch was dead while the attaching stem continued to grow.

Wood Knot

Knots materially affect cracking and warping, ease in working, and cleavability of timber. They are defects which weaken timber and lower its value for structural purposes where strength is an important consideration. The weakening effect is much more serious when timber is subjected to forces perpendicular to the grain and/or tension than where under load along the grain and/or compression. The extent to which knots affect the strength of a beam depends upon their position, size, number, and condition. A knot on the upper side is compressed, while one on the lower side is subjected to tension. If there is a season check in the knot, as is often the case, it will offer little resistance to this tensile stress. Small knots, however, may be located along the neutral plane of a beam and increase the strength by preventing longitudinal shearing. Knots in a board or plank are least injurious when they extend through it at right angles to its broadest surface. Knots which occur near the ends of a beam do not weaken it. Sound knots which occur in the central portion one-fourth the height of the beam from either edge are not serious defects.^[6]

Knots do not necessarily influence the stiffness of structural timber, this will depend on the size and location. Stiffness and elastic strength are more dependent upon the sound wood than upon localized defects. The breaking strength is very susceptible to defects. Sound knots do not weaken wood when subject to compression parallel to the grain.

In some decorative applications, wood with knots may be desirable to add visual interest. In applications where wood is painted, such as skirting boards, fascia boards, door frames and furniture, resins present in the timber may continue to 'bleed' through to the surface of a knot for months or even years after manufacture and show as a yellow or brownish stain. A knot primer paint or solution, correctly applied during preparation, may do much to reduce this problem but it is difficult to control completely, especially when using mass-produced kiln-dried timber stocks.

Heartwood and sapwood[link]

A section of a Yew branch showing 27 annual growth rings, pale sapwood and dark heartwood, and pith (centre dark spot). The dark radial lines are small knots.

Heartwood (or duramen^[7]) is wood that as a result of a naturally occurring chemical transformation has become more resistant to decay. Heartwood formation occurs spontaneously (it is a genetically programmed process). Once heartwood formation is complete, the heartwood is dead.^[8] Some uncertainty still exists as to whether heartwood is truly dead, as it can still chemically react to decay organisms, but only once.^[9]

Usually heartwood looks different; in that case it can be seen on a cross-section, usually following the growth rings in shape. Heartwood may (or may not) be much darker than living wood. It may (or may not) be sharply distinct from the sapwood. However, other processes, such as decay, can discolor wood, even in woody plants that do not form heartwood, with a similar color difference, which may lead to confusion.

Sapwood (or alburnum^[7]) is the younger, outermost wood; in the growing tree it is living wood,^[8] and its principal functions are to conduct water from the roots to the leaves and to store up and give back according to the season the reserves prepared in the leaves. However, by the time they become competent to conduct water, all xylem tracheids and vessels have lost their cytoplasm and the cells are therefore functionally dead. All wood in a tree is first formed as sapwood. The more leaves a tree bears and the more vigorous its growth, the larger the volume of sapwood required. Hence trees making rapid growth in the open have thicker sapwood for their size than trees of the same species growing in dense forests. Sometimes trees (of species that do form heartwood) grown in the open may become of considerable size, 30 cm or more in diameter, before any heartwood begins to form, for example, in second-growth hickory, or open-grown pines.

The term heartwood derives solely from its position and not from any vital importance to the tree. This is evidenced by the fact that a tree can thrive with its heart completely decayed. Some species begin to form heartwood very early in life, so having only a thin layer of live sapwood, while in others the change comes slowly. Thin sapwood is characteristic of such species as chestnut, black locust, mulberry, osage-orange, and sassafras, while in maple, ash, hickory, hackberry, beech, and pine, thick sapwood is the rule. Others never form heartwood.

No definite relation exists between the annual rings of growth and the amount of sapwood. Within the same species the cross-sectional area of the sapwood is very roughly proportional to the size of the crown of the tree. If the rings are narrow, more of them are required than where they are wide. As the tree gets larger, the sapwood must necessarily become thinner or increase materially in volume. Sapwood is thicker in the upper portion of the trunk of a tree than near the base, because the age and the diameter of the upper sections are less.

When a tree is very young it is covered with limbs almost, if not entirely, to the ground, but as it grows older some or all of them will eventually die and are either broken off or fall off. Subsequent growth of wood may completely conceal the stubs which will however remain as knots. No matter how smooth and clear a log is on the outside, it is more or less knotty near the middle. Consequently the sapwood of an old tree, and particularly of a forest-grown tree, will be freer from knots than the inner heartwood. Since in most uses of wood, knots are defects that weaken the timber and interfere with its ease of working and other properties, it follows that a given piece of sapwood, because of its position in the tree, may well be stronger than a piece of heartwood from the same tree.

It is remarkable that the inner heartwood of old trees remains as sound as it usually does, since in many cases it is hundreds, and in a few instances thousands, of years old. Every broken limb or root, or deep wound from fire, insects, or falling timber, may afford an entrance for decay, which, once started, may penetrate to all parts of the trunk. The larvae of many insects bore into the trees and their tunnels remain indefinitely as sources of weakness. Whatever advantages, however, that sapwood may have in this connection are due solely to its relative age and position.

If a tree grows all its life in the open and the conditions of soil and site remain unchanged, it will make its most rapid growth in youth, and gradually decline. The annual rings of growth are for many years quite wide, but later they become narrower and narrower. Since each succeeding ring is laid down on the outside of the wood previously formed, it follows that unless a tree materially increases its production of wood from year to year, the rings must necessarily become thinner as the trunk gets wider. As a tree reaches maturity its crown becomes more open and the annual wood production is lessened, thereby reducing still more the width of the growth rings. In the case of forest-grown trees so much depends upon the competition of the trees in their struggle for light and nourishment that periods of rapid and slow growth may alternate. Some trees, such as southern oaks, maintain the same width of ring for hundreds of years. Upon the whole, however, as a tree gets larger in diameter the width of the growth rings decreases.

Different pieces of wood cut from a large tree may differ decidedly, particularly if the tree is big and mature. In some trees, the wood laid on late in the life of a tree is softer, lighter, weaker, and more even-textured than that produced earlier, but in other trees, the reverse applies. This may or may not correspond to heartwood and sapwood. In a large log the sapwood, because of the time in the life of the tree when it was grown, may be inferior in hardness, strength, and toughness to equally sound heartwood from the same log. In a smaller tree, the reverse may be true.

Color[link]

In species which show a distinct difference between heartwood and sapwood the natural color of heartwood is usually darker than that of the sapwood, and very frequently the contrast is conspicuous (see section of yew log above). This is produced by deposits in the heartwood of chemical substances, so that a dramatic color difference does not mean a dramatic difference in the mechanical properties of heartwood and sapwood, although there may be a dramatic chemical difference.

Some experiments on very resinous Longleaf Pine specimens indicate an increase in strength, due to the resin which increases the strength when dry. Such resin-saturated heartwood is called "fat lighter". Structures built of fat lighter are almost impervious to rot and termites; however they are very flammable. Stumps of old longleaf pines are often dug, split into small pieces and sold as kindling for fires. Stumps thus dug may actually remain a century or more since being cut. Spruce impregnated with crude resin and dried is also greatly increased in strength thereby.

The wood of Coast Redwood is distinctively red in color

Since the latewood of a growth ring is usually darker in color than the earlywood, this fact may be used in judging the density, and therefore the hardness and strength of the material. This is particularly the case with coniferous woods. In ring-porous woods the vessels of the early wood not infrequently appear on a finished surface as darker than the denser latewood, though on cross sections of heartwood the reverse is commonly true. Except in the manner just stated the color of wood is no indication of strength.

Abnormal discoloration of wood often denotes a diseased condition, indicating unsoundness. The black check in western hemlock is the result of insect attacks. The reddish-brown streaks so common in hickory and certain other woods are mostly the result of injury by birds. The discoloration is merely an indication of an injury, and in all probability does not of itself affect the properties of the wood. Certain rot-producing fungi impart to wood characteristic colors which thus become symptomatic of weakness; however an attractive effect known as spalting produced by this process is often considered a desirable characteristic. Ordinary sap-staining is due to fungal growth, but does not necessarily produce a weakening effect.

Water content[link]

Water occurs in living wood in three conditions, namely: (1) in the cell walls, (2) in the protoplasmic contents of the cells, and (3) as free water in the cell cavities and spaces. In heartwood it occurs only in the first and last forms. Wood that is thoroughly air-dried retains 8–16% of the water in the cell walls, and none, or practically none, in the other forms. Even oven-dried wood retains a small percentage of moisture, but for all except chemical purposes, may be considered absolutely dry.

The general effect of the water content upon the wood substance is to render it softer and more pliable. A similar effect of common observation is in the softening action of water on paper or cloth. Within certain limits, the greater the water content, the greater its softening effect.

Drying produces a decided increase in the strength of wood, particularly in small specimens. An extreme example is the case of a completely dry spruce block 5 cm in section, which will sustain a permanent load four times as great as a green (undried) block of the same size will.^{[citation needed]}

The greatest strength increase due to drying is in the ultimate crushing strength, and strength at elastic limit in endwise compression; these are followed by the modulus of rupture, and stress at elastic limit in cross-bending, while the modulus of elasticity is least affected.

Structure[link]

Wood is a heterogeneous, hygroscopic, cellular and anisotropic material. It is composed of cells, and the cell walls are composed of micro-fibrils of cellulose (40% – 50%) and hemicellulose (15% – 25%) impregnated with lignin (15% – 30%).^[10]

Sections of tree trunk

A tree trunk as found at the Veluwe, Netherlands

In coniferous or softwood species the wood cells are mostly of one kind, tracheids, and as a result the material is much more uniform in structure than that of most hardwoods. There are no vessels ("pores") in coniferous wood such as one sees so prominently in oak and ash, for example.

The structure of hardwoods is more complex.^[11] The water conducting capability is mostly taken care of by vessels: in some cases (oak, chestnut, ash) these are quite large and distinct, in others (buckeye, poplar, willow) too small to be seen without a hand lens. In discussing such woods it is customary to divide them into two large classes, ring-porous and diffuse-porous. In ring-porous species, such as ash, black locust, catalpa, chestnut, elm, hickory, mulberry, and oak, the larger vessels or pores (as cross sections of vessels are called) are localised in the part of the growth ring formed in spring, thus forming a region of more or less open and porous tissue. The rest of the ring, produced in summer, is made up of smaller vessels and a much greater proportion of wood fibers. These fiber are the elements which give strength and toughness to wood, while the vessels are a source of weakness.

Magnified cross-section of Black Walnut, showing the vessels, rays (white lines) and annual rings: this is intermediate between diffuse-porous and ring-porous, with vessel size declining gradually

In diffuse-porous woods the pores are evenly sized so that the water conducting capability is scattered throughout the growth ring instead of being collected in a band or row. Examples of this kind of wood are basswood, birch, buckeye, maple, poplar, and willow. Some species, such as walnut and cherry, are on the border between the two classes, forming an intermediate group.

Earlywood and latewood in softwood[link]

earlywood and latewood in a softwood; radial view, growth rings closely spaced in a Pseudotsuga taxifolia

In temperate softwoods there often is a marked difference between latewood and earlywood. The latewood will be denser than that formed early in the season. When examined under a microscope the cells of dense latewood are seen to be very thick-walled and with very small cell cavities, while those formed first in the season have thin walls and large cell cavities. The strength is in the walls, not the cavities. Hence the greater the proportion of latewood the greater the density and strength. In choosing a piece of pine where strength or stiffness is the important consideration, the principal thing to observe is the comparative amounts of earlywood and latewood. The width of ring is not nearly so important as the proportion and nature of the latewood in the ring.

If a heavy piece of pine is compared with a lightweight piece it will be seen at once that the heavier one contains a larger proportion of latewood than the other, and is therefore showing more clearly demarcated growth rings. In white pines there is not much contrast between the different parts of the ring, and as a result the wood is very uniform in texture and is easy to work. In hard pines, on the other hand, the latewood is very dense and is deep-colored, presenting a very decided contrast to the soft, straw-colored earlywood.

It is not only the proportion of latewood, but also its quality, that counts. In specimens that show a very large proportion of latewood it may be noticeably more porous and weigh considerably less than the latewood in pieces that contain but little. One can judge comparative density, and therefore to some extent strength, by visual inspection.

No satisfactory explanation can as yet be given for the exact mechanisms determining the formation of earlywood and latewood. Several factors may be involved. In conifers, at least, rate of growth alone does not determine the proportion of the two portions of the ring, for in some cases the wood of slow growth is very hard and heavy, while in others the opposite is true. The quality of the site where the tree grows undoubtedly affects the character of the wood formed, though it is not possible to formulate a rule governing it. In general, however, it may be said that where strength or ease of working is essential, woods of moderate to slow growth should be chosen.

Earlywood and latewood in ring-porous woods[link]

Earlywood and latewood in a ring-porous wood (ash) in a Fraxinus excelsior ; tangential view, wide growth rings

In ring-porous woods each season's growth is always well defined, because the large pores formed early in the season abut on the denser tissue of the year before.

In the case of the ring-porous hardwoods there seems to exist a pretty definite relation between the rate of growth of timber and its properties. This may be briefly summed up in the general statement that the more rapid the growth or the wider the rings of growth, the heavier, harder, stronger, and stiffer the wood. This, it must be remembered, applies only to ring-porous woods such as oak, ash, hickory, and others of the same group, and is, of course, subject to some exceptions and limitations.

In ring-porous woods of good growth it is usually the latewood in which the thick-walled, strength-giving fibers are most abundant. As the breadth of ring diminishes, this latewood is reduced so that very slow growth produces comparatively light, porous wood composed of thin-walled vessels and wood parenchyma. In good oak these large vessels of the earlywood occupy from 6 to 10 percent of the volume of the log, while in inferior material they may make up 25% or more. The latewood of good oak is dark colored and firm, and consists mostly of thick-walled fibers which form one-half or more of the wood. In inferior oak, this latewood is much reduced both in quantity and quality. Such variation is very largely the result of rate of growth.

Wide-ringed wood is often called "second-growth", because the growth of the young timber in open stands after the old trees have been removed is more rapid than in trees in a closed forest, and in the manufacture of articles where strength is an important consideration such "second-growth" hardwood material is preferred. This is particularly the case in the choice of hickory for handles and spokes. Here not only strength, but toughness and resilience are important. The results of a series of tests on hickory by the U.S. Forest Service show that:

"The work or shock-resisting ability is greatest in wide-ringed wood that has from 5 to 14 rings per inch (rings 1.8-5 mm thick), is fairly constant from 14 to 38 rings per inch (rings 0.7–1.8 mm thick), and decreases rapidly from 38 to 47 rings per inch (rings 0.5–0.7 mm thick). The strength at maximum load is not so great with the most rapid-growing wood; it is maximum with from 14 to 20 rings per inch (rings 1.3–1.8 mm thick), and again becomes less as the wood becomes more closely ringed. The natural deduction is that wood of first-class mechanical value shows from 5 to 20 rings per inch (rings 1.3–5 mm thick) and that slower growth yields poorer stock. Thus the inspector or buyer of hickory should discriminate against timber that has more than 20 rings per inch (rings less than 1.3 mm thick). Exceptions exist, however, in the case of normal growth upon dry situations, in which the slow-growing material may be strong and tough."^[12]

The effect of rate of growth on the qualities of chestnut wood is summarised by the same authority as follows:

"When the rings are wide, the transition from spring wood to summer wood is gradual, while in the narrow rings the spring wood passes into summer wood abruptly. The width of the spring wood changes but little with the width of the annual ring, so that the narrowing or broadening of the annual ring is always at the expense of the summer wood. The narrow vessels of the summer wood make it richer in wood substance than the spring wood composed of wide vessels. Therefore, rapid-growing specimens with wide rings have more wood substance than slow-growing trees with narrow rings. Since the more the wood substance the greater the weight, and the greater the weight the stronger the wood, chestnuts with wide rings must have stronger wood than chestnuts with narrow rings. This agrees with the accepted view that sprouts (which always have wide rings) yield better and stronger wood than seedling chestnuts, which grow more slowly in diameter."^[12]

Earlywood and latewood in diffuse-porous woods[link]

In the diffuse-porous woods, the demarcation between rings is not always so clear and in some cases is almost (if not entirely) invisible to the unaided eye. Conversely, when there is a clear demarcation there may not be a noticeable difference in structure within the growth ring.

In diffuse-porous woods, as has been stated, the vessels or pores are even-sized, so that the water conducting capability is scattered throughout the ring instead of collected in the earlywood. The effect of rate of growth is, therefore, not the same as in the ring-porous woods, approaching more nearly the conditions in the conifers. In general it may be stated that such woods of medium growth afford stronger material than when very rapidly or very slowly grown. In many uses of wood, total strength is not the main consideration. If ease of working is prized, wood should be chosen with regard to its uniformity of texture and straightness of grain, which will in most cases occur when there is little contrast between the latewood of one season's growth and the earlywood of the next.

Monocot wood[link]

Trunks of the Coconut palm, a monocot, in Java. From this perspective these look not much different from trunks of a dicot or conifer

Structural material that roughly (in its gross handling characteristics) resembles ordinary, "dicot" or conifer wood is produced by a number of monocot plants, and these also are colloquially called wood. Of these, bamboo, botanically a member of the grass family, has considerable economic importance, larger culms being widely used as a building and construction material in their own right and, these days, in the manufacture of engineered flooring, panels and veneer. Another major plant group that produce material that often is called wood are the palms. Of much less importance are plants such as Pandanus, Dracaena and Cordyline. With all this material, the structure and composition of the structural material is quite different from ordinary wood.

Hard and soft woods[link]

There is a strong relationship between the properties of wood and the properties of the particular tree that yielded it. The density of wood varies with species. The density of a wood correlates with its strength (mechanical properties). For example, mahogany is a medium-dense hardwood that is excellent for fine furniture crafting, whereas balsa is light, making it useful for model building. One of the densest woods is black ironwood.

It is common to classify wood as either softwood or hardwood. The wood from conifers (e.g. pine) is called softwood, and the wood from dicotyledons (usually broad-leaved trees, e.g. oak) is called hardwood. These names are a bit misleading, as hardwoods are not necessarily hard, and softwoods are not necessarily soft. The well-known balsa (a hardwood) is actually softer than any commercial softwood. Conversely, some softwoods (e.g. yew) are harder than many hardwoods.

Chemistry of wood[link]

Aside from water, wood has three main components. Cellulose, a crystalline polymer derived from glucose, constitutes about 41–43%. Next in abundance is hemicellulose, which is around 20% in deciduous trees but near 30% in conifers. It is mainly five-carbon sugars that are linked in an irregular manner, in contrast to the cellulose. Lignin is the third component at around 27% in coniferous wood vs 23% in deciduous trees. Lignin confers the hydrophobic properties reflecting the fact that it is based on aromatic rings. These three components are interwoven, and direct covalent linkages exist between the lignin and the hemicellulose. A major focus of the paper industry is the separation of the lignin from the cellulose, from which paper is made.

Chemical structure of lignin, which comprises approximately 30% of wood and is responsible for many of its properties.

In chemical terms, the difference between hardwood and softwood is reflected in the composition of the constituent lignin. Hardwood lignin is primarily derived from sinapyl alcohol and coniferyl alcohol. Softwood lignin is mainly derived from coniferyl alcohol.^[13]

Extractives[link]

Aside from the lignocellulose, wood consists of a variety of low molecular weight organic compounds, called extractives. The wood extractives are fatty acids, resin acids, waxes and terpenes.^[14] For example, rosin is exuded by conifers as protection from insects. The extraction of these organic materials from wood provides tall oil, terpentine, and rosin.^[15]

Uses[link]

Fuel[link]

Wood has a long history of being used as fuel, which continues to this day, mostly in rural areas of the world. Hardwood is preferred over softwood because it creates less smoke and burns longer. Adding a woodstove or fireplace to a home is often felt to add ambiance and warmth.^[16]

The churches of Kizhi, Russia are among a handful of World Heritage Sites built entirely of wood, without metal joints. See Kizhi Pogost for more details.

The complex carpentry of the Centre Pompidou-Metz museum, Metz.

Construction[link]

Wood has been an important construction material since humans began building shelters, houses and boats. Nearly all boats were made out of wood until the late 19th century, and wood remains in common use today in boat construction.

Wood to be used for construction work is commonly known as lumber in North America. Elsewhere, lumber usually refers to felled trees, and the word for sawn planks ready for use is timber.

New domestic housing in many parts of the world today is commonly made from timber-framed construction. Engineered wood products are becoming a bigger part of the construction industry. They may be used in both residential and commercial buildings as structural and aesthetic materials.

In buildings made of other materials, wood will still be found as a supporting material, especially in roof construction, in interior doors and their frames, and as exterior cladding.

Wood is also commonly used as shuttering material to form the mould into which concrete is poured during reinforced concrete construction.

Furniture and utensils[link]

Wood has always been used extensively for furniture, such as chairs and beds. Also for tool handles and cutlery, such as chopsticks, toothpicks, and other utensils, like the wooden spoon.

Engineered wood[link]

Wood can be cut into straight planks and made into a wood flooring.

Engineered wood products, glued building products "engineered" for application-specific performance requirements, are often used in construction and industrial applications. Glued engineered wood products are manufactured by bonding together wood strands, veneers, lumber or other forms of wood fiber with glue to form a larger, more efficient composite structural unit.^[18] These products include glued laminated timber (glulam), wood structural panels (including plywood, oriented strand board and composite panels), laminated veneer lumber (LVL) and other structural composite lumber (SCL) products, parallel strand lumber, and I-joists.^[18] Approximately 100 million cubic meters of wood was consumed for this purpose in 1991.^[2] The trends suggest that particle board and fiber board will overtake plywood.

Engineered wood products display highly predictable and reliable performance characteristics and provide enhanced design flexibility: on one hand, these products allow the use of smaller pieces, and on the other hand, they allow for bigger spans. They may also be selected for specific projects such as public swimming pools or ice rinks where the wood will not deteriorate in the presence of certain chemicals, and are less susceptible to the humidity changes commonly found in these environments.

Engineered wood products prove to be more environmentally friendly and, if used appropriately, are often less expensive than building materials such as steel or concrete. These products are extremely resource-efficient because they use more of the available resource with minimal waste. In most cases, engineered wood products are produced using faster growing and often underutilized wood species from managed forests and tree farms.^[19]

Wood unsuitable for construction in its native form may be broken down mechanically (into fibers or chips) or chemically (into cellulose) and used as a raw material for other building materials, such as engineered wood, as well as chipboard, hardboard, and medium-density fiberboard (MDF). Such wood derivatives are widely used: wood fibers are an important component of most paper, and cellulose is used as a component of some synthetic materials. Wood derivatives can also be used for kinds of flooring, for example laminate flooring.

Next generation wood products[link]

Further developments include new lignin glue applications, recyclable food packaging, rubber tire replacement applications, anti-bacterial medical agents, and high strength fabrics or composites.^[20] As scientists and engineers further learn and develop new techniques to extract various components from wood, or alternatively to modify wood, for example by adding components to wood, new more advanced products will appear on the marketplace.

In the arts[link]

Artists can use wood to create delicate sculptures.

Stringed instrument bows are often made from pernambuco or brazilwood.

Wood has long been used as an artistic medium. It has been used to make sculptures and carvings for millennia. Examples include the totem poles carved by North American indigenous people from conifer trunks, often Western Red Cedar (Thuja plicata), and the Millennium clock tower,^[21] now housed in the National Museum of Scotland^[22] in Edinburgh.

It is also used in woodcut printmaking, and for engraving.

Certain types of musical instruments, such as those of the violin family, the guitar, the clarinet and recorder, the xylophone, and the marimba, are made mostly or entirely of wood. The choice of wood may make a significant difference to the tone and resonant qualities of the instrument, and tonewoods have widely differing properties, ranging from the hard and dense african blackwood (used for the bodies of clarinets) to the light but resonant European spruce (Picea abies) (traditionally used for the soundboards of violins). The most valuable tonewoods, such as the ripple sycamore (Acer pseudoplatanus), used for the backs of violins, combine acoustic properties with decorative color and grain which enhance the appearance of the finished instrument.

Despite their collective name, not all woodwind instruments are made entirely of wood. The reeds used to play them, however, are usually made from Arundo donax, a type of monocot cane plant.

Sports and recreational equipment[link]

Many types of sports equipment are made of wood, or were constructed of wood in the past. For example, cricket bats are typically made of white willow. The baseball bats which are legal for use in Major League Baseball are frequently made of ash wood or hickory, and in recent years have been constructed from maple even though that wood is somewhat more fragile. In softball, however, bats are more commonly made of aluminium (this is especially true for fastpitch softball).

Many other types of sports and recreation equipment, such as skis, ice hockey sticks, lacrosse sticks and archery bows, were commonly made of wood in the past, but have since been replaced with more modern materials such as aluminium, fiberglass, carbon fiber, titanium, and composite materials. One noteworthy example of this trend is the golf club commonly known as the wood, the head of which was traditionally made of persimmon wood in the early days of the game of golf, but is now generally made of synthetic materials.

Medicine[link]

In January 2010 Italian scientists announced that wood could be harnessed to become a bone substitute. It is likely to take at least five years until this technique will be applied for humans.^[23]

See also[link]

Notes[link]

References[link]

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Tiger Woods
Woods at a Chevron World Challenge charity event (2011)
Personal information
Full name	Eldrick Tont Woods
Nickname	Tiger
Born	(1975-12-30) December 30, 1975 (age 36) Cypress, California
Height	6 ft 1 in (1.85 m)
Weight	185 lb (84 kg; 13.2 st)
Nationality	United States
Residence	Jupiter Island, Florida
Spouse	Elin Nordegren (2004–2010)
Children	Sam Alexis (b. 2007) Charlie Axel (b. 2009)
Career
College	Stanford University (two years)
Turned professional	1996
Current tour(s)	PGA Tour (joined 1996)
Professional wins	99[1]
Number of wins by tour
PGA Tour	72 (3rd all time)
European Tour	38 (3rd all time)[2][3]
Japan Golf Tour	2
Asian Tour	1
PGA Tour of Australasia	1
Other	16
Best results in Major Championships (Wins: 14)
Masters Tournament	Won: 1997, 2001, 2002, 2005
U.S. Open	Won: 2000, 2002, 2008
The Open Championship	Won: 2000, 2005, 2006
PGA Championship	Won: 1999, 2000, 2006, 2007
Achievements and awards
PGA Tour Rookie of the Year	1996
PGA Player of the Year	1997, 1999, 2000, 2001, 2002, 2003, 2005, 2006, 2007, 2009
PGA Tour Player of the Year	1997, 1999, 2000, 2001, 2002, 2003, 2005, 2006, 2007, 2009
PGA Tour leading money winner	1997, 1999, 2000, 2001, 2002, 2005, 2006, 2007, 2009
Vardon Trophy	1999, 2000, 2001, 2002, 2003, 2005, 2007, 2009
Byron Nelson Award	1999, 2000, 2001, 2002, 2003, 2005, 2006, 2007, 2009
FedEx Cup Champion	2007, 2009
(For a full list of awards, see here)

Eldrick Tont "Tiger" Woods (born December 30, 1975)^[4][5] is an American professional golfer whose achievements to date rank him among the most successful golfers of all time. Formerly the World No. 1, he is the highest-paid professional athlete in the world, having earned an estimated US$90.5 million from winnings and endorsements in 2010.^[6][7]

Woods turned professional in 1996, and by April 1997 he had already won his first major, the 1997 Masters. He first reached the number one position in the world rankings in June 1997. Through the 2000s, Woods was the dominant force in golf, spending 264 weeks from August 1999 to September 2004 and 281 weeks from June 2005 to October 2010 as world number one. From December 2009 to early April 2010, Woods took leave from professional golf to focus on his marriage after he admitted infidelity. His multiple infidelities were revealed by several different women, through many worldwide media sources.^[8] This was followed by a loss of form, and his ranking gradually fell to a low of #58 in November 2011.^[7][9] He snapped a career-long winless streak of 107 weeks when he captured the Chevron World Challenge in December 2011.^[9] As of April 8, 2012, he is ranked #8.^[10]

Woods has broken numerous golf records. He has been world number one for the most consecutive weeks and for the greatest total number of weeks of any other golfer. He has been awarded PGA Player of the Year a record ten times,^[11] the Byron Nelson Award for lowest adjusted scoring average a record eight times, and has the record of leading the money list in nine different seasons. He has won 14 professional major golf championships, the second highest of any player (Jack Nicklaus leads with 18), and 72 PGA Tour events, third all time behind Sam Snead and Nicklaus.^[12] He has more career major wins and career PGA Tour wins than any other active golfer does. He is the youngest player to achieve the career Grand Slam, and the youngest and fastest to win 50 tournaments on tour. Additionally, Woods is only the second golfer, after Jack Nicklaus, to have achieved a career Grand Slam three times. Woods has won 16 World Golf Championships, and won at least one of those events in each of the first 11 years after they began in 1999.

Background and family[link]

Woods was born Eldrick Tont Woods in Cypress, California, to Earl (1932–2006) and Kultida (Tida) Woods (born 1944). He is the only child of their marriage, but does have two half-brothers, Earl Jr. (born 1955) and Kevin (born 1957), and a half-sister, Royce (born 1958) from the 18-year marriage of Earl Woods and his first wife, Barbara Woods Gray.^[13] Earl, a retired lieutenant colonel and Vietnam War veteran, was of mixed African American, Chinese, and Native American ancestry. Kultida (née Punsawad), originally from Thailand (where Earl had met her on a tour of duty in 1968), is of mixed Thai, Chinese, and Dutch ancestry. This makes Woods himself half Asian (one-quarter Chinese and one-quarter Thai), one-quarter African American, one-eighth Native American, and one-eighth Dutch.^[14] He refers to his ethnic make-up as "Cablinasian" (a syllabic abbreviation he coined from Caucasian, Black, American Indian, and Asian).^[15]

Woods' first name, Eldrick, was coined by his mother because it began with "E" (for Earl) and ended with "K" (for Kultida). His middle name Tont is a traditional Thai name. He was nicknamed Tiger in honor of his father's friend Col. Vuong Dang Phong, who had also been known as Tiger.^[16]

Woods has a niece, Cheyenne Woods, who is an amateur golfer on Wake Forest University's golf team.^[17]

Early life and amateur golf career[link]

Woods grew up in Orange County, California. He was a child prodigy, introduced to golf before the age of two, by his athletic father Earl, a single-figure handicap amateur golfer who had been one of the earliest African-American college baseball players at Kansas State University.^[18] In 1978, Tiger putted against comedian Bob Hope in a television appearance on The Mike Douglas Show. At age three, he shot a 48 over nine holes over the Cypress Navy course, and at age five, he appeared in Golf Digest and on ABC's That's Incredible.^[19] Before turning seven, Tiger won the Under Age 10 section of the Drive, Pitch, and Putt competition, held at the Navy Golf Course in Cypress, California.^[20] In 1984 at the age of eight, he won the 9–10 boys' event, the youngest age group available, at the Junior World Golf Championships.^[21] He first broke 80 at age eight.^[22] He went on to win the Junior World Championships six times, including four consecutive wins from 1988 to 1991.^{[23][24][25][26][27]}

Woods' father Earl wrote that Tiger first beat him when he was 11 years old, with Earl trying his best. Earl lost to Tiger every time from then on.^[28][29] Woods first broke 70 on a regulation golf course at age 12.^[30]

Woods' first major national junior tournament was the 1989 Big I, when he was 13 years old. Woods was paired with pro John Daly, then relatively unknown, in the final round; the event's format placed a professional with each group of juniors who had qualified. Daly birdied three of the last four holes to beat Woods by only one stroke.^[31] As a young teenager, Woods first met Jack Nicklaus in Los Angeles at the Bel-Air Country Club, when Nicklaus was performing a clinic for the club's members. Woods was part of the show, and impressed Nicklaus and the crowd with his skills and potential.^[32] Earl Woods had researched in detail the career accomplishments of Nicklaus, and had set his young son the goals of breaking those records.^[30]

While attending Western High School in Anaheim at the age of 15, Woods became the youngest ever U.S. Junior Amateur champion (a record which stood until it was broken by Jin Liu in 2010).^[33] He was named 1991's Southern California Amateur Player of the Year (for the second consecutive year) and Golf Digest Junior Amateur Player of the Year. In 1992, he defended his title at the U.S. Junior Amateur Championship, becoming the first multiple winner; competed in his first PGA Tour event, the Nissan Los Angeles Open (he missed the 36-hole cut); and was named Golf Digest Amateur Player of the Year, Golf World Player of the Year, and Golfweek National Amateur of the Year.^[34][35]

The following year, Woods won his third consecutive U.S. Junior Amateur Championship; he remains the event's only three-time winner.^[36] In 1994, at the TPC at Sawgrass in Florida, he became the youngest-ever winner of the U.S. Amateur Championship, a record that stood until 2008 when it was broken by Danny Lee.^[37] He was a member of the American team at the 1994 Eisenhower Trophy World Amateur Golf Team Championships (winning), and the 1995 Walker Cup (losing).^[38][39]

Woods graduated from Western High School in 1994 at age 18, and was voted "Most Likely to Succeed" among the graduating class. He had starred for the high school's golf team under coach Don Crosby.^[40]

College golf career[link]

Woods was recruited very heavily by college golf powers, and chose Stanford University, the 1994 NCAA Division I champion. He enrolled at Stanford in the fall of 1994 under a golf scholarship, winning his first collegiate event, the 40th Annual William H. Tucker Invitational, that September.^[41] He declared a major in economics, and was nicknamed "Urkel" by college teammate Notah Begay III.^[42] In 1995, he successfully defended his U.S. Amateur title at the Newport Country Club in Rhode Island^[37] and was voted Pac-10 Player of the Year, NCAA First Team All-American, and Stanford's Male Freshman of the Year (an award that encompasses all sports).^[43][44] He participated in his first PGA Tour major, the 1995 Masters Tournament, and tied for 41st as the only amateur to make the cut. At age 20 in 1996, he became the first golfer to win three consecutive U.S. Amateur titles^[45] and won the NCAA individual golf championship.^[46] In winning the Silver Medal as leading amateur at The Open Championship, he tied the record for an amateur aggregate score of 281.^[47] He left college after two years and turned professional.

Professional career[link]

Woods in 2001

Woods became a professional golfer in August 1996, and immediately signed deals with Nike, Inc. and Titleist that ranked as the most lucrative endorsement contracts in golf history at that time.^[48][49] Woods was named Sports Illustrated's 1996 Sportsman of the Year and PGA Tour Rookie of the Year.^[50] In April 1997, he won his first major, the Masters, becoming the tournament's youngest-ever winner.^[51] Two months later, he set the record for the fastest-ever ascent to #1 in the Official World Golf Rankings.^[52] After a lackluster 1998, Woods finished the 1999 season with eight wins, including the PGA Championship, a feat not achieved since 1974.^[53][54]

In 2000, Woods achieved six consecutive wins, the longest winning streak since 1948. One of these was the 2000 U.S. Open, where he broke or tied nine tournament records in what Sports Illustrated called "the greatest performance in golf history."^[55] At age 24, he became the youngest golfer to achieve the Career Grand Slam.^[56] At the end of 2000, Woods had won nine of the twenty PGA Tour events he entered and had broken the record for lowest scoring average in tour history. He was named the Sports Illustrated Sportsman of the Year, the first and only athlete to be honored twice, and was ranked by Golf Digest magazine as the twelfth-best golfer of all time.^[57][58]

Woods at the 2004 Ryder Cup

Woods' victory in the 2001 Masters Tournament made him the first player to hold all four major professional golf titles at the same time.^[59] Following a stellar 2001 and 2002 in which Woods continued to dominate the tour, Woods' career hit a "slump".^[53][60] He did not win a major in 2003 or 2004. In September 2004, Vijay Singh overtook Woods in the Official World Golf Rankings, breaking Woods' record streak of 264 weeks at #1.^[61] Woods rebounded in 2005, winning six official PGA Tour money events and reclaiming the top spot in July after swapping it back and forth with Singh over the first half of the year.^[62]

In 2006, Woods began dominantly, winning his first two PGA tournaments but failing to capture his fifth Masters championship in April.^[63][64] Following the death of his father in May, Woods took a nine-week hiatus from the tour and appeared rusty upon his return at the U.S. Open, missing the cut at Winged Foot.^[65] However, he quickly returned to form and ended the year by winning six consecutive tour events. At the season's close, with 54 wins and 12 majors wins, Woods had broken the tour records for both total wins and total majors wins over eleven seasons.^[66]

Woods at the 2006 Masters Tournament

He continued to excel in 2007 and the first part of 2008. In April 2008, he underwent knee surgery and missed the next two months on the tour.^[67] Woods returned for the 2008 U.S. Open, where he struggled the first day but ultimately claimed a dramatic victory over Rocco Mediate, after which Mediate said, "This guy does things that are just not normal by any stretch of the imagination," and Kenny Perry added, "He beat everybody on one leg."^[68][69][70] Two days later, Woods announced that he would miss the remainder of the season due to further knee surgery, and that his knee was more severely damaged than previously revealed, prompting even greater praise for his U.S. Open performance. Woods called it "my greatest ever championship."^[71][72][73] In Woods' absence, TV ratings for the remainder of the season suffered a huge decline from 2007.^[74]

Upon Woods' much-anticipated return in 2009, he performed well, including a spectacular performance at the 2009 Presidents Cup, but failed to win a major, the first year since 2004 that he failed to do so.^[75][76][77] After his marital infidelities came to light at the end of 2009 and received massive media coverage, Woods announced in December that he would be taking an indefinite break from competitive golf. In February 2010, he delivered a televised apology for his behavior. During this period, several companies ended their endorsement deals with Woods.

He returned to competition in April at the 2010 Masters Tournament, where he finished in a tie for fourth place.^[78] He followed the Masters with poor showings at the Quail Hollow Championship and the Players Championship, where he withdrew in the fourth round citing injury.^[79] Shortly afterward, Woods' coach since 2003, Hank Haney, resigned the position; he was replaced in August by Sean Foley. The rest of the season went badly for Woods, who failed to win a single event for the first time since turning professional, while nevertheless finishing the season ranked #2 in the world.

Woods' performance continued to suffer in 2011, taking its toll on his ranking. After falling to #7 in March, he rebounded to #5 with a strong showing at the 2011 Masters Tournament, where he tied for fourth place.^[80][81][82] Due to leg injuries incurred at the Masters, he missed several summer events; in July he fired his longtime caddy Steve Williams, replacing him temporarily with friend Bryon Bell.^[83][84] After returning to tournament play in August, Woods continued to falter, and his ranking gradually fell to a low of #58.^[9] He rose to #50 in mid-November after a third-place win at the Emirates Australian Open, and broke his winless streak with a victory at December's Chevron World Challenge.^[9][85]

His 2012 season started at the Abu Dhabi HSBC Golf Championship on the European Tour in late January. For the first two days of play Tiger was grouped with Rory McIlroy and world No.1 Luke Donald. He shot under par rounds of 70 and 69 on Thursday and Friday respectively, which left him in joint 4th place at 5-under par. His low round of the week came on Saturday, shooting a 6-under par 66, giving him the joint lead with England's Robert Rock. Woods struggled on Sunday and couldn't mount a big enough charge, shooting a level par 72 and settling for joint 3rd place. Woods' second tournament of the year came at the AT&T Pebble Beach National Pro-Am in early February which he had not played since 2002. His amateur partner for the week was Dallas Cowboys quarterback Tony Romo. Woods shot solid rounds of 68-68-67 on the first three days, and began Sunday in third place, four shots behind leader Charlie Wi. However, he struggled with his putting and shot a final round 75 while his playing partner Phil Mickelson shot a 64 and won the tournament.

His next tournament was the WGC-Accenture Match Play Championship in Arizona. Woods battled to win his first round match against Gonzalo Fernández-Castaño, 1-up, and then played Nick Watney in the second round. On the 18th hole, Woods had to make birdie to extend the match, however his 5 foot putt missed and he was knocked out of the tournament. Woods commented that his putting was hindered technically and required some work after battling with it throughout the round.^[86] The following week Woods teed off at the Honda Classic in Palm Beach Gardens, Florida. Woods commented that he had referred back to putting basics instead of new technique he had been applying. Woods' putting over the first three days of tournament play was noticeably better, but the ball was struggling to fall into the hole. Tiger began the fourth round on 2-under par, 9 shots behind leader Rory McIlroy. After parring the first hole and being delayed by adverse weather, Woods returned and played the remaining 17 holes in 8-under par including two eagles and no bogeys. A birdie-eagle finish set up Woods to possibly claim the title, however McIlroy kept his cool and won the tournament. Tiger finished joint second, and the round also marked his lowest final round score in his PGA Tour career.

Woods played the following week at the WGC-Cadillac Championship in Miami, Florida. Tiger spent the first three days near the top of the leaderboard and shot 72-67-68 to start the fourth round in tied 8th place at 9-under par, 8 shots behind leader Bubba Watson. Woods struggled on the front 9 and shot 2-over par going out. He then began to noticeably limp on the next three holes and went on to withdraw from the tournament with an apparent left leg injury, which was later confirmed as a strain on his left Achilles tendon that had been injured previously at the 2011 Masters Tournament. After a short time off, Woods played in the Tavistock Cup at the Lake Nona Golf and Country Club, representing Team Albany, finishing 4th. The same week, Woods began the Arnold Palmer Invitational. After three rounds of 69, 65 and a 71, he began Sunday in the lead at 11-under par, one shot ahead of Graeme McDowell. Woods remained in the lead throughout the round and shot a 2-under par 70 to claim his seventh win at Bay Hill and also marked his first win on the PGA Tour since the BMW Championship in September 2009. After a week off, he returned to Augusta for the Masters Tournament. Over the four days, Woods was never close to contending the title, and shot rounds of 72-75-72-74 to finish tied 40th. After a 3 week break from competition, Woods traveled to Charlotte, North Carolina, for the Wells Fargo Championship. Although starting positively with a 1-under par 71, Woods' second round of 73 (1-over) derailed his tournament hopes and resulted in him missing his eighth cut as a professional by 1 shot and second in as many years for the tournament. The following week, Woods played The Players Championship. After an opening round of 74 (2-over), he was in threat of missing a second consecutive cut, a first for his professional career, however after a 4-under 68, he was firmly staying in the tournament as well as being in the hunt for the weekend. However, a weekend charge never mounted despite good ball striking and he settled for T40th at 1-under par.

Endorsements[link]

Woods has been called the world's most marketable athlete.^[87] Shortly after his 21st birthday in 1996, he began signing endorsement deals with numerous companies, including General Motors, Titleist, General Mills, American Express, Accenture, and Nike, Inc. In 2000, he signed a 5-year, $105 million contract extension with Nike. It was the largest endorsing deal ever signed by an athlete at that time.^[88] Woods' endorsement has been credited with playing a significant role in taking the Nike Golf brand from a "start-up" golf company earlier in the past decade, to becoming the leading golf apparel company in the world, and a major player in the equipment and golf ball market.^[87][89] Nike Golf is one of the fastest growing brands in the sport, with an estimated $600 million in sales.^[90] Woods has been described as the "ultimate endorser" for Nike Golf,^[90] frequently seen wearing Nike gear during tournaments, and even in advertisements for other products.^[88] Woods receives a cut from the sales of Nike Golf apparel, footwear, golf equipment, golf balls,^[87] and has a building named after him at Nike’s headquarters campus in Beaverton, Oregon.^[91]

In 2002, Woods was involved in every aspect of the launch of Buick's Rendezvous SUV. A company spokesman stated that Buick is happy with the value of Woods' endorsement, pointing out that more than 130,000 Rendezvous vehicles were sold in 2002 and 2003. "That exceeded our forecasts," he was quoted as saying, "It has to be in recognition of Tiger." In February 2004, Buick renewed Woods' endorsement contract for another five years, in a deal reportedly worth $40 million.^[88]

Woods collaborated closely with TAG Heuer to develop the world's first professional golf watch, released in April 2005.^[92] The lightweight, titanium-construction watch, designed to be worn while playing the game, incorporates numerous innovative design features to accommodate golf play. It is capable of absorbing up to 5,000 Gs of shock, far in excess of the forces generated by a normal golf swing.^[92] In 2006, the TAG Heuer Professional Golf Watch won the prestigious iF product design award in the Leisure/Lifestyle category.^[93]

Woods preparing for a photo shoot in 2006

Woods also endorses the Tiger Woods PGA Tour series of video games; he has done so since 1999.^[94] In 2006, he signed a six-year contract with Electronic Arts, the series' publisher.^[95]

In February 2007, along with Roger Federer and Thierry Henry, Woods became an ambassador for the "Gillette Champions" marketing campaign. Gillette did not disclose financial terms, though an expert estimated the deal could total between $10 million and $20 million.^[96]

In October 2007, Gatorade announced that Woods would have his own brand of sports drink starting in March 2008. "Gatorade Tiger" was his first U.S. deal with a beverage company and his first licensing agreement. Although no figures were officially disclosed, Golfweek magazine reported that it was for five years and could pay him as much as $100 million.^[97] The company decided in early fall 2009 to discontinue the drink due to weak sales.^[98]

According to Golf Digest, Woods made $769,440,709 from 1996 to 2007,^[99] and the magazine predicted that by 2010, Woods would pass one billion dollars in earnings.^[100] In 2009, Forbes confirmed that Woods was indeed the world's first athlete to earn over a billion dollars in his career (before taxes), after accounting for the $10 million bonus Woods received for the FedEx Cup title.^[101][102] The same year, Forbes estimated his net worth to be $600 million, making him the second richest "African American" behind only Oprah Winfrey.^[103]

Honors[link]

Woods driving in 2007

On August 20, 2007, California Governor Arnold Schwarzenegger and First Lady Maria Shriver announced that Woods would be inducted into the California Hall of Fame. He was inducted December 5, 2007 at The California Museum for History, Women and the Arts in Sacramento.^[104][105]

He has been named "Athlete of the Decade" by the Associated Press in December 2009.^[106] He has been named Associated Press Male Athlete of the Year a record-tying four times, and is the only person to be named Sports Illustrated's Sportsman of the Year more than once.

Since his record-breaking win at the 1997 Masters Tournament, golf's increased popularity is commonly attributed to Woods' presence. He is credited by some sources for dramatically increasing prize money in golf, generating interest in new audiences, and for drawing the largest TV audiences in golf history.^{[50][107][108][109][110][111]}

Tiger-proofing[link]

Early in Woods' career, a small number of golf experts expressed concern about his impact on the competitiveness of the game and the public appeal of professional golf. Sportswriter Bill Lyon of Knight-Ridder asked in a column, "Isn't Tiger Woods actually bad for golf?" (though Lyon ultimately concluded that he was not).^[112] At first, some pundits feared that Woods would drive the spirit of competition out of the game of golf by making existing courses obsolete and relegating opponents to simply competing for second place each week.

A related effect was measured by economist Jennifer Brown of the University of California, Berkeley who found that other golfers played worse when competing against Woods than when he was not in the tournament. The scores of highly skilled (exempt) golfers are nearly one stroke higher when playing against Woods. This effect was larger when he was on winning streaks and disappeared during his well-publicized slump in 2003–04. Brown explains the results by noting that competitors of similar skill can hope to win by increasing their level of effort, but that, when facing a "superstar" competitor, extra exertion does not significantly raise one's level of winning while increasing risk of injury or exhaustion, leading to reduced effort.^[113]

Many courses in the PGA Tour rotation (including Major Championship sites like Augusta National) began to add yardage to their tees in an effort to slow down long hitters like Woods, a strategy that became known as "Tiger-Proofing". Woods himself welcomed the change as he believes adding yardage to the course does not affect his ability to win.^[114]

Playing style[link]

Woods practicing before 2004 Ryder Cup at Oakland Hills Country Club in Bloomfield Hills, Michigan

When Woods first joined the professional tour in 1996, his long drives had a large impact on the world of golf.^[115][116] However, when he did not upgrade his equipment in the following years (insisting upon the use of True Temper Dynamic Gold steel-shafted clubs and smaller steel clubheads that promoted accuracy over distance),^[117] many opponents caught up to him. Phil Mickelson even made a joke in 2003 about Woods using "inferior equipment", which did not sit well with Nike, Titleist or Woods.^[118][119] During 2004, Woods finally upgraded his driver technology to a larger clubhead and graphite shaft, which, coupled with his clubhead speed, made him one of the Tour's lengthier players off the tee once again.

Despite his power advantage, Woods has always focused on developing an excellent all-around game. Although in recent years he has typically been near the bottom of the Tour rankings in driving accuracy, his iron play is generally accurate, his recovery and bunker play is very strong, and his putting (especially under pressure) is possibly his greatest asset. He is largely responsible for a shift to higher standards of athleticism amongst professional golfers, and is known for putting in more hours of practice than most.^{[120][121][122]}

From mid-1993, while he was still an amateur, until 2004, Woods worked almost exclusively with leading swing coach Butch Harmon. From mid-1997, Harmon and Woods fashioned a major redevelopment of Woods' full swing, achieving greater consistency, better distance control, and better kinesiology. The changes began to pay off in 1999.^[123] From March 2004 to 2010, Woods was coached by Hank Haney, who worked on flattening his swing plane. Woods continued to win tournaments with Haney, but his driving accuracy dropped significantly. Haney resigned in May 2010 and was replaced by Sean Foley. ^[124]

Mike "Fluff" Cowan served as Woods' caddy from the start of his professional career until March 1999.^[125] He was replaced by Steve Williams, who became a close friend of Woods and is often credited with helping him with key shots and putts.^[126] In June 2011, Woods fired Williams and replaced him with Woods' friend Bryon Bell, on an interim basis. Joe LaCava, a former caddy of both Fred Couples and Dustin Johnson, was hired by Woods shortly after.^{[citation needed]}

Equipment[link]

As of 2011:^{[127][128][129]}

• Driver: Nike VR Tour (8.5 degree; Graphite Design Tour AD DI 6x shaft)
• Fairway Woods: Nike VR Pro 15° 3-wood and Nike SQ II 19° 5-Wood with Mitsubishi Diamana Blueboard 103 shaft
• Irons: Nike VR Pro Blades (2-PW) (Tiger will put his 5 Wood or 2 Iron in the bag depending upon the course setup and conditions). All irons are 1 degree upright, have D4 swingweight, standard size Tour Velvet grips and True Temper Dynamic Gold X-100 shafts.^[130]
• Wedges: Nike VR Pro (56 and 60 degree; True Temper Dynamic Gold S400 shafts)
• Putter: Nike Method 001
• Ball: Nike ONE Tour D (with "Tiger" imprint)
• Golf Glove: Nike Dri-FIT Tour glove
• Golf Shoes: Nike TW '13
• Driver club cover: Frank, a plush tiger head club cover created by his mother. Frank has appeared in several commercials.^[131]

Career achievements[link]

Woods has won 72 official PGA Tour events including 14 majors. He is 14–1 when going into the final round of a major with at least a share of the lead. He has been heralded as "the greatest closer in history" by multiple golf experts.^{[132][133][134]} He owns the lowest career scoring average and the most career earnings of any player in PGA Tour history.

He has spent the most consecutive and cumulative weeks atop the world rankings. He is one of five players (along with Gene Sarazen, Ben Hogan, Gary Player, and Jack Nicklaus) to have won all four professional major championships in his career, known as the Career Grand Slam, and was the youngest to do so.^[135] Woods is the only player to have won all four professional major championships in a row, accomplishing the feat in the 2000–2001 seasons.

• PGA Tour wins (72)
• European Tour wins (38)
• Japan Golf Tour wins (2)
• Asian Tour wins (1)
• PGA Tour of Australasia wins (1)
• Other professional wins (15)
• Amateur wins (21)

Major championships[link]

Wins (14)[link]

Year	Championship	54 Holes	Winning Score	Margin	Runner(s)-up
1997	Masters Tournament	099 shot lead	-18−18 (70–66–65–69=270)	1212 strokes	Tom Kite
1999	PGA Championship	00Tied for lead	-11−11 (70–67–68–72=277)	011 stroke	Sergio García
2000	U.S. Open	1010 shot lead	-12−12 (65–69–71–67=272)	1515 strokes	Ernie Els, Miguel Ángel Jiménez
2000	The Open Championship	066 shot lead	-19−19 (67–66–67–69=269)	088 strokes	Thomas Bjørn, Ernie Els
2000	PGA Championship (2)	011 shot lead	-18−18 (66–67–70–67=270)	00Playoff 1	Bob May
2001	Masters Tournament (2)	011 shot lead	-16−16 (70–66–68–68=272)	022 strokes	David Duval
2002	Masters Tournament (3)	00Tied for lead	-12−12 (70–69–66–71=276)	033 strokes	Retief Goosen
2002	U.S. Open (2)	044 shot lead	-03−3 (67–68–70–72=277)	033 strokes	Phil Mickelson
2005	Masters Tournament (4)	033 shot lead	-12−12 (74–66–65–71=276)	00Playoff 2	Chris DiMarco
2005	The Open Championship (2)	022 shot lead	-14−14 (66–67–71–70=274)	055 strokes	Colin Montgomerie
2006	The Open Championship (3)	011 shot lead	-18−18 (67–65–71–67=270)	022 strokes	Chris DiMarco
2006	PGA Championship (3)	00Tied for lead	-18−18 (69–68–65–68=270)	055 strokes	Shaun Micheel
2007	PGA Championship (4)	033 shot lead	-08−8 (71–63–69–69=272)	022 strokes	Woody Austin
2008	U.S. Open (3)	011 shot lead	-01−1 (72–68–70–73=283)	00Playoff 3	Rocco Mediate

¹ Defeated May in three-hole playoff by 1 stroke: Woods (3–4–5=12), May (4–4–5=13)
² Defeated DiMarco with birdie on first extra hole
³ Defeated Mediate with a par on 1st sudden death hole after 18-hole playoff was tied at even par

Results timeline[link]

LA = Low Amateur
DNP = Did not play
CUT = missed the half-way cut
"T" indicates a tie for a place
Green background for wins. Yellow background for top-10.

World Golf Championships[link]

Wins (16)[link]

Year	Championship	54 Holes	Winning Score	Margin of Victory	Runner(s)-up
1999	WGC-NEC Invitational	055 shot lead	-10-10 (66–71–62–71=270)	011 stroke	Phil Mickelson
1999	WGC-American Express Championship	-031 shot deficit	-06-6 (71–69–70–68=278)	00Playoff 1	Miguel Ángel Jiménez
2000	WGC-NEC Invitational (2)	099 shot lead	-21-21 (64–61–67–67=259)	1111 strokes	Justin Leonard, Phillip Price
2001	WGC-NEC Invitational (3)	-022 shot deficit	-12-12 (66–67–66–69=268)	00Playoff 2	Jim Furyk
2002	WGC-American Express Championship (2)	055 shot lead	-25-25 (65–65–67–66=263)	011 stroke	Retief Goosen
2003	WGC-Accenture Match Play Championship	n/an/a	n/a2 & 1	n/an/a	David Toms
2003	WGC-American Express Championship (3)	022 shot lead	-06-6 (67–66–69–72=274)	022 strokes	Stuart Appleby, Tim Herron, Vijay Singh
2004	WGC-Accenture Match Play Championship (2)	n/an/a	n/a3 & 2	n/an/a	Davis Love III
2005	WGC-NEC Invitational (4)	00Tied for lead	-06-6 (66–70–67–71=274)	011 stroke	Chris DiMarco
2005	WGC-American Express Championship (4)	-022 shot deficit	-10-10 (67–68–68–67=270)	00Playoff 3	John Daly
2006	WGC-NEC InvitationalWGC-Bridgestone Invitational (5)	-031 shot deficit	-10-10 (67–64–71–68=270)	00Playoff 4	Stewart Cink
2006	WGC-American Express Championship (5)	066 shot lead	-23-23 (63–64–67–67=261)	088 strokes	Ian Poulter, Adam Scott
2007	WGC-American Express ChampionshipWGC-CA Championship (6)	044 shot lead	-10-10 (71–66–68–73=278)	022 strokes	Brett Wetterich
2007	WGC-NEC InvitationalWGC-Bridgestone Invitational (6)	-031 shot deficit	-08-8 (68–70–69–65=272)	088 strokes	Justin Rose, Rory Sabbatini
2008	WGC-Accenture Match Play Championship (3)	n/an/a	n/a8 & 7	n/an/a	Stewart Cink
2009	WGC-NEC InvitationalzWGC-Bridgestone Invitational (7)	-013 shot deficit	-12-12 (68–70–65–65=268)	044 strokes	Robert Allenby, Pádraig Harrington

¹ Won on the first extra hole of a sudden-death playoff.
² Won on the seventh extra hole of a sudden-death playoff.
³ Won on the second extra hole of a sudden-death playoff.
⁴ Won on the fourth extra hole of a sudden-death playoff.

Results timeline[link]