Brackets
Assuming two competitors per match, if there are competitors, there will be rounds required, or if there are rounds, there will be competitors.
In the opening round, competitors will get a bye. Often, the number of participants in a single-elimination tournament is fixed as a power of two, so that nobody gets a bye. For example, the tennis Grand Slam singles championships are tournaments of 128 players. This ensures all competitors will face opponents who have previously played the same number of matches.
The full schedule of pairings across all rounds (the bracket) may be allocated before the start of the tournament, or each round may be allocated at the end of the preceding round. Each successive round halves the number of competitors remaining, assuming there are no byes.
Read more about this topic: Single-elimination Tournament