Butterfly is one of the four competitive swimming styles, along with freestyle, backstroke, and breaststroke. It is characterized by a simultaneous arm movement and a butterfly kick, which is a specific type of kick that involves both legs moving together in a dolphin-like motion.

In the butterfly stroke, the arms move symmetrically over the water, with the swimmer bringing both arms out of the water and then together over their head in a diving motion. The legs perform the butterfly kick, which provides propulsion and helps the swimmer maintain balance in the water.

Butterfly is considered one of the most challenging and strenuous of the four competitive swimming styles, as it requires a high level of coordination and strength. It is typically swum over shorter distances, such as the 100 meter butterfly. Despite the difficulty of the stroke, many swimmers enjoy the challenge and the feeling of power and speed it provides.