The Restricted Free Agent (RFA) system is a contractual mechanism used in major professional sports leagues such as the NBA, NHL, and NFL to regulate player movement after their initial contracts expire. Under this system, a restricted free agent can negotiate with other teams, but their original team has the right to match any offer the player receives, allowing them to retain the player under the same terms and restricting the player's ability to move. If the original team declines to match, the player is free to sign with the new team.