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 characterized by an alternating rotation of the arms toward the back; the outstretched legs make an alternating beating movement at the same time.
Movement for making a turn; the swimmer arrives in the dorsal position, pivots, then pushes from the wall with the feet.
Movement by which the swimmer starts from within the pool; at the signal, the swimmer lets go of the starting grip and then pushes from the wall with the feet.