Swimmers compete to achieve the fastest time while covering a designated distance using a predetermined stroke (freestyle, backstroke, breaststroke or butterfly). Although no specific stroke is prescribed for freestyle events, all swimmers currently use the crawl, which is the fastest stroke.
At Rio 2016, 32 men's and women's events were held in the pool, including individual and relay races. At Tokyo 2020, there will be 35 events, with the addition of three new competitions: 800m freestyle (men), 1,500m freestyle (women) and 4×100m medley relay (mixed).