Running is a method of terrestrial locomotion by which humans and other animals move quickly on foot. Running is a gait with an aerial phase in which all feet are above the ground (though there are exceptions). This is in contrast to walking, a slower form of movement where at least one foot is always in contact with the ground, the legs are kept mostly straight, and the center of gravity vaults over the stance leg or legs in an inverted pendulum fashion. A feature of a running body from the viewpoint of spring-mass mechanics is that changes in kinetic and potential energy within a stride co-occur, with energy storage accomplished by springy tendons and passive muscle elasticity. The term "running" can refer to a variety of speeds ranging from jogging to sprinting.

Running in humans is associated with improved health and life expectancy.

It is hypothesized that the ancestors of humankind developed the ability to run for long distances about 2.6 million years ago, probably to hunt animals. Competitive running grew out of religious festivals in various areas. Records of competitive racing date back to the Tailteann Games in Ireland between 1171 BCE and 632 BCE, while the first recorded Olympic Games took place in 776 BCE. Running has been described as the world's most accessible sport.