What does seeding mean in a tournament?

Seeding assigns a rank to each entrant and places them in the bracket so that higher-ranked competitors are separated as long as possible. In a standard single-elimination bracket, the top seed faces the lowest seed, the second faces the second lowest, and so on, so that the two strongest can only meet in the final if both keep winning. The purpose is to reward regular-season performance, avoid the anticlimax of the two best teams meeting in the opening round, and preserve competitive interest deep into the event. Without seeding, a random draw would frequently eliminate the strongest entrants early.

Seeds are determined differently across sports. Some use objective ranking systems computed from results, as tennis largely does. Some use committee selection weighing record, strength of schedule, and other factors, as the NCAA basketball tournament does through its selection committee. Some use league standings directly. The method matters because seeding conveys real advantage beyond the opponent draw, often including home venue and, in some formats, a bye through the opening round.

Upsets are the reason anyone watches. In the NCAA men's tournament, the first 16 over 1 upset did not occur until 2018 and has happened only rarely since, which makes it among the more notable results in American sport. In soccer's knockout competitions and in tennis majors, lower-ranked players beating top seeds is common enough to be expected somewhere in each event. That tension is the design working as intended: seeding raises the probability that the strongest reach the late rounds without guaranteeing it. Related terms worth knowing: a bye advances a team without playing, protected seeding prevents certain matchups such as teammates or same-country players meeting early, and reseeding recalculates the bracket after each round in some formats rather than fixing the path in advance.