The competition is a knockout tournament with pairings for each round drawn at random. There are no seeds and the draw for each round is not made until after the scheduled dates for the previous round (except for the Preliminary and First Qualifying Rounds which are drawn at the same time as the Extra Preliminary Round). The draw also determines which teams will play at home.
Each tie is played as a single leg. If a match is drawn, there is a replay, usually at the ground of the team who were away for the first game. Drawn replays are now settled with extra time and penalty shootouts