Freestyle means that the swimmer may swim any style, including a mix of them, except in a Medley event, where Freestyle means any style other than Backstroke, Breaststroke, or Butterfly.

Backstroke is swimming on your back. It has more constraints than Freestyle but is still more flexible than Breaststroke and Butterfly.

Breaststroke involves swimming by alternating one stroke and one kick, with the movements of the right arm and leg in sync with those of the left arm and leg.

Butterfly is swimming by alternating one stroke and two kicks, with the movements of the right arm and leg in sync with those of the left arm and leg.

Also known as Individual Medley or IM, it is the combination of four different styles, equally distributed to complete a distance. Perform the styles in the following sequence: Butterfly, Backstroke, Breaststroke, and Freestyle.

It is a team race where four swimmers take turns to complete a distance. Each swimmer covers a quater of the distance, which they can swim in any style they feel faster. Crawl is the most common choice.

It is a team race where four swimmers take turns to complete a distance. Each swimmer covers a quarter of the distance in a different style. The order of styles is different from Individual Medley because it would be difficult to start Backstroke in the middle of the race. So, the sequence is: Backstroke, Breaststroke, Butterfly, and Freestyle.