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 formally crowned under the former 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. The championship races for elite men and women was complemented with junior races, beginning in 1990, and with under-23 events from 2002.
Beginning with the 2009 racing season, the format of the ITU Triathlon World Championship was changed from a single championship race format to a series of world championship 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.