Keepers guard the goal hoops while Chasers try to throw the Quaffle through them. The Beaters use bats to drive Bludgers at the opposing players and disrupt play. Seekers fly through and above the action, watching for the Golden Snitch, since when they catch it the game is over. Professional Quidditch teams include a manager, trainers, and also mediwizards who can administer potions and healing spells as needed.
Teams are formed at Hogwarts and other wizarding schools. Professional teams form leagues all over the world. National teams compete against each other in friendly matches and also aspire to win the Quidditch World Cup.
Many witches and wizards play for recreation as well — the Weasley children formed impromptu teams and played two-a-side matches in the back pasture at the Burrow:
Harry, Ron, Fred, and George were planning to go up the hill to a small paddock the Weasleys owned. It was surrounded by trees that blocked it from view of the village below, meaning that they could practice Quidditch there, as long as they didn’t fly too high (CS4).