The Glicko Rating system is a method used to calculate the skill levels of players in competitive games. Developed by Mark Glickman, it improves upon traditional rating systems like Elo by incorporating a measure of uncertainty in a player's skill level. This uncertainty is represented by a value called the "rating deviation," which adjusts based on the player's performance over time. In the Glicko system, players earn ratings based on their match outcomes, with higher ratings indicating better skill. The system also updates a player's rating and rating deviation after each match, allowing for more accurate assessments of player abilities as they compete against others.