Swimming is the set of activities practiced in water such as swimming in a basin (swimming pool) or outdoors (open water). Swimming has been an Olympic sport since 1896 for men and 1912 for women.
There are 4 types of swimming in competitive swimming: breaststroke, freestyle, backstroke and butterfly, and two different pool lengths: the 25m small pool and the 50m large pool. The latter is the one that hosts the Olympic competitions every 4 years.
The breaststroke, backstroke and butterfly cover 3 distances: the 50, 100 and 200 meters. In theory, freestyle allows all styles of swimming, but in practice the front crawl, the fastest stroke, is used. It has 3 additional distances: the 400, the 800 and the 1,500 meters.
Of the 40 events practiced, only 32 are contested at the Olympic Games. The 50-meter butterfly, backstroke and breaststroke as well as the 800-meter freestyle for women and the 1500-meter freestyle for men are not part of the Olympic program. They are contested in other competitions such as the World or European Championships.
Open water swimming has been an Olympic discipline since the Beijing Games in 2008 which is held in a natural environment. The 10 km event is the only one to have entered the Olympic program.