types of strokes 
Four basic categories are recognized by the International Amateur Swimming Federation (FINA): the breaststroke, the butterfly, the backstroke and freestyle (the crawl).
Stroke on the stomach in which the two arms are thrust simultaneously toward the front and then brought backward.
Movement for making a half turn; the swimmer touches the wall with both hands, pivots, then pushes from the wall with the feet.
Vertical simultaneous movement of the legs that completes an undulation started by the upper body; the legs always stay together.