Quidditch Through the Ages is the title of a book that Harry Potter first spotted in Ron Weasley’s (admittedly small) collection and borrowed in an effort to learn more about this popular wizarding sport that he’d never heard of before his first trip to Diagon Alley. Hagrid’s attempts to explain the rules told him practically nothing then when he met Draco Malfoy for the first time the sport was mentioned but that was about it (along the lines of “Do you play?” and “Do you have a favorite team?”).
Then Harry met Ron, and Ron explained the rules to him (sort of), but Harry still didn’t know much about the sport until McGonagall introduced him to Oliver Wood, who seemed to be the only person capable of sensibly explaining the rules of the game to anyone (probably because of his obsession with love for the game).
Harry finally broke down and ordered his own copy of Quidditch Through the Ages by owl so he wouldn’t have to keep borrowing Ron’s, and amazingly it seems to have escaped their habit of writing notes in and around most of the pages, as they did with Harry’s copy of Fantastic Beasts and Where to Find Them (notes written to each other, commentary on certain creatures, even a game of hangman in the back). I suppose it was out of respect for the subject matter, as they both easily were way more interested in Quidditch than in magical creatures. Either way, I’m sure the book would thank them if it could.
It turns out there’s a lot more to the game than we get to see in the books, having been around for centuries (since about the 1300s, when the Golden Snitch was invented—a similar but differently-named ball was used before that), and in the first Quidditch World Cup, held in 1473, all 700 known fouls were committed by both teams before it was over. That’s an awful lot of fouls! Anyway, I’m glad I’m not on the committee that has to decide those things, or there would probably be 1000 different fouls mentioned in the rule book. 😛