A triathlon is a multisport race with three continuous and sequential endurance races. The word is of Greek origin, from τρεῖς or treis (three) and ἆθλος or athlos (competition).[2] While variations of the sport exist, the most common form includes swimming, cycling, and running over various distances. Triathletes compete for fastest overall course completion, including timed transitions between the three races. Source :