GT League is a racing game mode featured in the Gran Turismo series, specifically designed for players to compete in various events and championships. It offers a structured environment where players can race different cars across multiple tracks, showcasing their skills and strategies. In GT League, players can earn rewards and unlock new vehicles by completing races and challenges. The mode includes a variety of categories, such as Beginner League, Amateur League, and Professional League, catering to different skill levels and providing a comprehensive racing experience for both casual and competitive gamers.