Quidditch? You don't know what Quidditch is? I thought you Muggles knew everything about our lives.
It's a sport that you play on brooms. You have two teams with seven players each: Three Chasers. Two Beaters. One Keeper. One Seeker.
The Keeper is like the goalie in your footie games. The Keeper keeps the Quaffle (that's one of the four balls. One Quaffle, Two Bludgers, and One Golden Snitch) out of the three goals. There are six in total. Three on each side. They're these tall metal posts with hoops on the top. The Chasers score by throwing the Quaffles past the Keeer and into the hoops.
You have the two Beaters for the two Bludgers. Beaters have bats. They're job is to keep the bludgers from knocking people off their team, especially if it's the seeker, off of their brooms and hit it on the other side to distract the other players. The Seeker's job is to catch the Golden Snitch. It's a tiny ball, that is bloody fast. You catch the Snitch you win the game, since the Snitch is the most points. Though there have been a few games where a team still managed to lose even though they caught the Snitch. But that's not that common.