A triathlon is an endurance-based sporting event that combines three physical activities–swimming, bicycling and marathon running–in rapid and direct succession. Between each activity is a transition period during which participants can change clothes, stow the gear from the previous activity (e.g. swimsuits and goggles) and retrieve triathlon gear for the next activity. Transition periods, even the time it takes to change clothes, are included in the overall time limit of the event, so transitions shouldn’t be treated as a “rest period” and the nonstop nature of the triathlon is maintained at all times.
The transition areas are numbered in consecutive order; the area between the swimming and bicycling activities is called T1 for “transition 1” and the area between the bicycling and marathon running activities is called T2 for “transition 2”.
The four commonly accepted distances for triathlons are, from longest to shortest, Ultra Distance, Long Course, Intermediate Distance and Sprint Distance. The Ultra Distance in particular is famous worldwide for being the length of the grueling Ironman Triathlon. The swimming, bicycling and running triathlon as we know it today originated in France in the 1920s. Prior to swimming, cycling and marathon running becoming the standard, there were triple-sport events held with canoeing in place of the swimming, and with the three sports featured in the modern triathlon but not performed in the specific order required today.
The first American triathlon to be called a triathlon specifically had a total of 46 participants, and was held in 1974 in San Diego, California. Today, the Ironman Triathlon garners participation from tens of thousands of people per year, and only those who complete one of the qualifying races or who win a special lottery drawing (roughly 200 drawings are made from a pool of 30,000 annually) may go on to the world championship Ironman Triathlon.