Elo leaderboards are a method for ranking players in competitive games. The basic idea is that each player has a rating, which is a number that represents their skill level. When two players play against each other, the ratings of the players are used to predict the outcome of the game. After the game is played, the actual outcome is compared to the predicted outcome, and the ratings of the players are adjusted accordingly.

The adjustment is based on the difference between the predicted outcome and the actual outcome, with larger adjustments made for more unexpected results. This means that if a player with a lower rating beats a player with a higher rating, their rating will increase more than if they had beaten a player with a similar rating. The opposite is also true, if a player with a higher rating loses to a player with a lower rating, their rating will decrease more.

The Elo rating system was designed to be self-correcting, meaning that as more games are played, the ratings of the players will converge towards their true skill level. The system also allows for the calculation of the probability of a player winning against another player, given the two players' ratings.