The ITU World Triathlon Series is the International Triathlon Union's annual series of triathlon events used to crown an annual world champion. There are eight rounds of competitions culminating in a Grand Final race. Athletes compete head-to-head for points in these races that will determine the overall ITU world champion. In 2013, the series offered a total of $2.25 million in prize money to elite athletes, making it the richest series in triathlon. The elite championship races are held over the standard (Olympic) distance of 1500 m mass-start open-water swim, 40 km draft-legal cycle and 10 km run.
The world champion was formerly crowned in the ITU Triathlon World Championship, a single championship race that was held annually from 1989, the same year as the formation of the International Triathlon Union (ITU), to 2008. Beginning with the 2009 racing season the ITU Triathlon World Championship was changed to a series of events culminating with a grand final race. From 2009 to 2011 the events were known as the World Championship Series (WCS) before being relabeled World Triathlon Series (WTS) in 2012.