Hiking is a long, vigorous walk, usually on trails or footpaths in the countryside. Walking for pleasure developed in Europe during the eighteenth century. Religious pilgrimages have existed much longer but they involve walking long distances for a spiritual purpose associated with specific religions.

Walking is one of the main gaits of terrestrial locomotion among legged animals. Walking 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 usable number of limbs—even arthropods, with six, eight, or more limbs, walk. In humans, walking has health benefits including improved mental health and reduced risk of cardiovascular disease and death.