Quidditch is a 7v7 team sport based on the sport of the same name in the Harry Potter books.
The basic mechanics of the game are illustrated in this video.
A handy image is also provided here: (usquidditch.org)
USQ Rulebook 10 is linked here. (usquidditch.org)
An abridged rulebook is linked here. (victoriaquidditch.org)