Quidditch is a favourite sport of wizards. It is played on broomsticks in the air, with four balls--two Bludgers, one Quaffle, and a Golden Snitch--and seven players on each team--three Chasers, two Beaters, a Keeper and a Seeker.
There are three goal posts at each end of a Quidditch pitch, fifty feet tall, with a hoop at the top of each. The Chasers try to put the Quaffle through one of the opposing team's hoops, scoring ten points every time they do so. The Keepers try to prevent the other team's Chasers from scoring.
There are two Bludgers in play during the game, zooming around and trying to knock players off their brooms. Each team's Beaters are armed with wooden bats and charged with the duty of knocking the Bludgers away from their own team's players and towards the other team's.
The fourth ball, the Golden Snitch, is much smaller, about the size of a large walnut, with tiny silver wings. The Seekers' job is to catch the Snitch. When the Golden Snitch is caught, the team whose Seeker caught it gets 150 points, and the game ends.