Wiffleball (also known as whiffleball) is based on baseball. The main variation is that both the ball and bat are plastic. Additionally, the ball is perforated and light in weight.

Wiffleball is a variation of baseball played either indoor or outdoor, and is perfect for a confined area. It is played with a hollow plastic ball that allows pitchers to throw a variety of curveballs, risers, and sinkers. The bat used for wiffleball is most often thin, 31 inches long, and made of plastic.

The goal of wiffleball is to score more runs than the opposing team at the end of the game.

Unlike baseball, there is no ball chasing or base running. The field is laid out with foul lines and markers for singles, doubles triples and home run areas. Ideal dimensions for the field are 20 feet wide at the home run marker and 60 feet long. A game can be played with as little as one player per team, and as much as five players per team. With five players on a team, the defensive alignment is a pitcher, a catcher, and a double, triple and home run area fielder. Fielders cannot move from one area to another when a full team is playing. Three outs retire the side; outs are made in the same way as baseball except for when a ground ball is caught when still in motion. Scoring follows the same rules as baseball.

In 1953, David N. Mullany invented wiffleball when he designed a perforated ball that his 12 year old son could easily curve. The game became popular in the 1960s and 70s as a backyard game played at picnics and sandlots. Wiffleball is now a registered trademark of The Wiffle Ball, Inc.

Bat
Field Markers
Wiffle Ball

Wiffleball is an easy sport to get involved in and can be learned rather quickly. Pitchers must learn to grip the ball in order to throw various pitches like curves, sinkers, and risers. On offense, batters train to improve their timing and hand to eye coordination.

Wiffle Ball - baseball sized hollow ball made out of plastic

http://www.wiffle.com/about_rules.htm