Just as Oliver Wood gave Harry a crash course in Quidditch, I'll be doing the same here, for any that are new to the sport. I'll also include a bit on brooms.
The field is oval in shape, with six fifty-foot-high hoops, three at each end. The stands are raised, so the fans can keep up on the action without craning their necks too much.
There are four balls used in a game of Quidditch. The largest is the Quaffle, a bright red ball. It has no special properties.
Next are the Bludgers. They're like cannonballs. They fly around the field, trying to hit anyone they can.
Last, and smallest of all, is the Golden Snitch. To quote Oliver, "It's wicked fast and damn near impossible to see." They also have flesh memories, which I'll get into later.
There are seven players on a team. The three Chasers throw the Quaffle to each other and try to get it through one of the hoops. Ten points for every score.
The Keeper guards the poles, to prevent the other team from scoring. Keepers usually guard the center hoop, which lets them move quickly to the others.
The Beaters carry small bats. They try to hit the Bludgers at the opposing team, while protecting their teammates. There haven't been any deaths by Bludger at Hogwarts, just broken bones.
The Seeker tries to catch the Snitch before the opposing Seeker. Capture of the Snitch earns that team one hundred and fifty points.
OTHER POINTS TO CONSIDER
Seekers are usually light and fast. They have to chase down the smallest ball of the lot.
Snitches have flesh memories. In case of a disputed capture, the Snitch will remember the first person to touch it. Being so small, they make perfect hiding places for small objects.
There isn't really much to say here. Which Broomstick or Quidditch Through the Ages could give you a detailed summary of various brooms. Just keep in mind that different brooms have different qualities. Each new model usually has better performance than the old models of any make.
LENGTH OF THE GAME
A game of Quidditch only ends when the Seeker catches the Snitch. The record for longest match is about three months. Reserves had to be brought on so the players could sleep. Most Hogwarts matches last an hour or two, at most.
I hope this little guide is helpful. Don't forget to comment. And be sure to try out for your House team.