The Elo Rating System is a method used to calculate the relative skill levels of players in two-player games, such as chess. Developed by Hungarian-American mathematician Arpad Elo, the system assigns a numerical rating to each player, which changes based on the outcome of matches. When a player wins, their rating increases, while the opponent's rating decreases, reflecting the match's result and the players' previous ratings. This system allows for a dynamic ranking of players, making it easier to compare skill levels across different competitions. The Elo system is widely used in various games and sports, including chess, tennis, and video games, providing a standardized way to assess player performance.