Softball was invented in 1887 in Chicago, USA as a direct off-shoot of baseball. The key differences between traditional Softball and baseball are that in Softball:

• The ball is always pitched under-arm. In baseball the ball is usually pitched over-arm. For an exciting demonstration of the difference between softball and baseball pitching see episode 7 of FSN Sport Science on You Tube.
• The regulation ball is larger, less dense and heavier than a regulation baseball. It is however not particularly soft, especially when pitched at speed!
• The bats used are generally not as thick as baseball bats. However, at the junior level softball and baseball bats are interchangeable
• The diamond and the playing field are usually smaller
• The game is 7 innings long, as opposed to 9 innings in professional baseball
• The pitcher's area is a flat circle (in baseball it's a raised mound) and generally the pitching distance is shorter
• A tie-breaker ruleis used after seven innings
• The re-entry rule is used
• A designated player (DP) can be used.