Walking (also known as ambulation) is one of the main gaits of locomotion among legged animals, and is typically slower than running and other gaits. Walking is defined by an 'inverted pendulum' gait in which the body vaults over the stiff limb or limbs with each step. This applies regardless of the number of limbs - even arthropods with six, eight or more limbs.

The word walk is descended from the Old English wealcan "to roll". In humans and other bipeds, walking is generally distinguished from running in that only one foot at a time leaves contact with the ground and there is a period of double-support. In contrast, running begins when both feet are off the ground with each step. This distinction has the status of a formal requirement in competitive walking events. For quadrupedal species, there are numerous gaits which may be termed walking or running, and distinctions based upon the presence or absence of a suspended phase or the number of feet in contact any time do not yield mechanically correct classification. The most effective method to distinguish walking from running is to measure the height of a person's center of mass using motion capture or a force plate at midstance. During walking, the center of mass reaches a maximum height at midstance while during running, it is at a minimum. Definitions based on the percent of the stride during which a foot is in contact with the ground (averaged across all feet) of greater than 50% contact corresponds well with identification of 'inverted pendulum' mechanics and are indicative of walking for animals with any number of limbs, although this definition is incomplete. Running humans and animals may have contact periods greater than 50% of a gait cycle when rounding corners, running uphill or carrying loads.

John R. "Johnny" Cash (February 26, 1932 – September 12, 2003), was an American singer-songwriter, actor, and author, who has been called one of the most influential musicians of the 20th century. Although he is primarily remembered as a country music icon, his songs and sound spanned many other genres including rockabilly and rock and roll—especially early in his career—as well as blues, folk, and gospel. This crossover appeal led to Cash being inducted in the Country Music Hall of Fame, the Rock and Roll Hall of Fame, and Gospel Music Hall of Fame.

Cash was known for his deep, distinctive bass-baritone voice; for the "boom-chicka-boom" sound of his Tennessee Three backing band; for his rebelliousness, coupled with an increasingly somber and humble demeanor; for providing free concerts inside prison walls; and for his dark performance clothing, which earned him the nickname "The Man in Black". He traditionally started his concerts by saying, "Hello, I'm Johnny Cash." and usually following it up with his standard "Folsom Prison Blues".