Wiffle ball is a scaled back variation of baseball that was developed in 1953 in Fairfield, Connecticut. Originally, it was intended to be played in confined space or otherwise small area, but became a popular outdoor activity. The sport is played using a perforated light-weight plastic ball and a long hollow plastic bat. Two teams of one to five players each attempt to advance imaginary runners to home plate, and score, based on where each batter places the ball on the field. The term Wiffle ball may refer to the sport as a whole, or the ball used in the sport. Wiffle is a registered trademark of Wiffle Ball, Inc. and was derived from the slang word whiff meaning to strike out.

The term diamond sports refers to recreational variants of baseball, a bat-and-ball sport. The major sport most related to baseball is the Olympic discipline of softball, with the two sports being administered internationally alongside Baseball5 by the World Baseball Softball Confederation.