There are 2 main versions of Softball. Other disciplines of Softball include modified fast pitch, co-ed softball, indoor-arena softball, beach softball and wheelchair softball.
Fast pitch allows 2 main underhand pitching deliveries, one involves an entire revolution and the other where the pitcher’s arm comes back and then forward.
Slow pitch requires the pitcher to lob the ball underhand with an arc that reaches a minimum height of 1.83 metres and a maximum height of 3.66 metres.
A modified fast pitch allows underhand deliveries but the arm must not make a complete revolution around the shoulder socket.