A triathlon is an endurance multisport race consisting of swimming, cycling, and running over various distances. Triathletes compete for fastest overall completion time, racing each segment sequentially with the time transitioning between the disciplines included.

The sport has its roots in multi-event races held in France during the 1920s, with more specified rules and races forming during the late 1970s as sports clubs and individuals developed the sport. This history has meant that variations of the sport were created and still exist. It also led to other three stage races using the name triathlon despite not being continuous or not consisting of swim, bike, and run elements.