The purpose of the tiebreaker in tennis matches is to determine the winner when the score is tied in a set, typically at 6-6. It is a special game played to a set number of points, usually 7, but a player must win by at least 2 points to secure the set. This process ensures matches conclude efficiently without extended play. Tiebreakers enhance the excitement and competitive nature of tennis, as players must demonstrate skill under pressure to clinch the set.