Ochre ( /ˈoʊkər/ OH-kər; from Greek: ὠχρός, ōkhrós, pale) is the term for both a golden-yellow or light yellow brown color and for a form of earth pigment which produces the color. The pigment can also be used to create a reddish tint known as "red ochre". The more rarely used terms "purple ochre" and "brown ochre" also exist for variant hues. Because of these other hues, the color ochre is sometimes referred to as "yellow ochre" or "gold ochre".

Ochres are among the earliest pigments used by mankind, derived from naturally tinted clay containing mineral oxides. Chemically, it is hydrated iron (III) oxide, mineralogically known as limonite. Modern artists' pigments continue to use the terms "yellow ochre" and "red ochre" for specific hues.

Ochre clays have been used medicinally from the earliest times. For example, such use is described in the Ebers Papyrus from Egypt, dating to about 1550 BC.

Ochres are non-toxic, and can be used to make an oil paint that dries quickly and covers surfaces thoroughly. To manufacture ground ochre, ochre clay is first mined from the ground. It is then washed in order to separate sand from ochre, which can be done by hand. The remaining ochre is then dried in the sun and sometimes burned to enhance the natural color.

Red is any of a number of similar colors evoked by light consisting predominantly of the longest wavelengths discernible by the human eye, in the wavelength range of roughly 630–740 nm. Longer wavelengths just past this range are called infrared (below red) and cannot be seen by the naked eye although they can be sensed as heat. In some cultures, certain shades of red are used to symbolize anger or aggression.

It is the color of blood when it is exposed to sunlight. In western countries, it is most commonly referred to as a color of evil, love, and sometimes, though rarely, happiness.

The word red comes from the Old English rēad. The word can be further traced to the Proto-Germanic rauthaz and the Proto-Indo European root reudh-. In Sanskrit, the word rudhira means red or blood. In the English language, the word red is associated with the color of blood, certain flowers (e.g., roses), and ripe fruits (e.g., apples, cherries). Fire is also strongly connected, as is the sun and the sky at sunset. Healthy, light-skinned people are sometimes said to have a "ruddy" complexion (as opposed to appearing pale). After the rise of socialism in the mid-19th century, red was used to symbolize and describe revolutionary movements.