:Walk redirects here. That term may also refer to a base on balls in baseball or walking (basketball).

Walking is the main form of animal locomotion on land, distinguished from running and crawling. When executed in shallow water, it is usually described as wading and when executed vertically it becomes scrambling or climbing. The word walking is derived from the Old English walcan (to roll).

Walking is generally distinguished from running in that only one foot at a time leaves contact with the ground: for humans and other bipeds 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, often resulting in disqualification even at the Olympic level.) For horses and other quadrupedal species, the running gaits may be numerous, and walking keeps three feet at a time on the ground.

The average child achieves independent walking ability between 9 and 15 months old.

While not strictly bipedal, several primarily bipedal human gaits (where the long bones of the arms support at most a small fraction of the bodies' weight) are generally regarded as variants of walking. These include:

Hand walking; an unusual form of locomotion, in which the walker moves primarily using his hands.

walking on crutches (usually executed by alternating between standing on both legs, and rocking forward "on the crutches" (i.e., supported under the armpits by them);

walking with one or two walking stick(s) or trekking poles (reducing the load on one or both legs, or supplementing the body's normal balancing mechanisms by also pushing against the ground through at least one arm that holds a long object);

walking while holding on to a walker, a framework to aid with balance; and

scrambling, using the arms (and hands or some other extension to the arms) not just as a backup to normal balance, but, as when walking on talus, to achieve states of balance that would be impossible or unstable when supported solely by the legs.