A triathlon is a grueling race consisting of a swim, followed by a bicycle race, followed by a run. The triathlon is an Olympic event for the first time in the 2000 Olympics in Sydney.

The segments of a triathlon have different lengths in different races, but the lengths used in the Olympics are typical: 1.5 km swim, 40 km bike, 10 km run.

These three segments are run consecutively; the racers report to prepared stations between segments to change equipment, e.g., to pick up/leave their bikes.

The Ironman is a long triathlon.