Chess.com uses the popular Round-Robin format for chess tournaments. In round-robin tournaments each player plays every other player in two games (once as white, once as black). An example of a small round-robin is shown below.
|1. Player 1 (1200)||X||½ - 1||1 -½||1 -1||5||11.5|
|2. Player 2 (1200)||0 -½||X||0 - 1||1 - ½||3||7.5|
|3. Player 3 (1200)||½ - 0||0 - 1||X||0 -½||2||6.5|
|4. Player 4 (1200)||0 - 0||½ - 0||½ - 1||X||2||4.5|
Round-robin is very effective because each player plays every other player and then the winner is determined by the score. However, if there are a lot of players, then round-robin tournaments can take a very long time. In that case a knock-out format can be introduced to make the tournament go faster.
keywords: tournament organization model swiss round robin pairings style