The four swimming strokes are freestyle, backstroke, breaststroke and butterfly. Competition races are held in each stroke (and a combination - known as the medley).
The breaststroke kick cannot come above the water and backstroke swimmers can only swim underwater for a distance of 15 metres from the start of the race. Officials monitor these requirements alongside the pool and at each end of the pool.
Except for backstroke, all races are started on the starting blocks and await the starter’s signal before diving in to commence the race. Backstroke swimmers start their races in the water. If a swimmer starts before the signal, the swimmer will be regarded as having false started and will be disqualified.
In international competition, swimmers compete at the distances of 50, 100, 200, 400, 800 and 1500 metres.
Swimmers don't just wear caps to keep their hair dry, they are also used to maximise their speed in the water. Swimmers wear swimming caps to streamline their movement through the water.
In recent times swimmers have started to wear bodysuits instead of traditional bathing costumes to increase efficiency in the water.