Running is a popular activity for people trying to stay in shape. As a cardiovascular or aerobic exercise, few things have as many of the positive health benefits as running.

A person who regularly runs has the benefit of weight loss, cardiovascular health, increased muscle mass and bone density; not to mention an improved emotional state via the reduction of stress.

Running is one of humankind's oldest pastimes. The history of the activity is as old as we are. Borne out of necessity, the earliest human ancestors had to run as a way of hunting down game and avoiding predators.

As a form of competition, running can be traced back to the earliest human civilizations. The word marathon is named after a city in ancient Greece. The modern marathon race received its name from the legend of Pheidippides, a Greek messenger who ran the entire length from Marathon to Athens to announce a Greek victory against the Persian Empire in the battle of Marathon before collapsing and dying. The modern marathon is an endurance race with an official distance of 42.2 kilometers.

Human beings are unique in the way they run. No other animal has the body mechanics to achieve full gait on two legs the way humans can.

Running differs from walking in that when a person walks, both feet simultaneously touch the ground while when a person runs, both feel leave the ground at once.

Running is at the core of a majority of track events which are races in which competitors are timed to see who can run a certain distance in the shortest amount of time.