In the sport of association football, a defender is an outfield player whose primary role is to stop attacks during the game and prevent the opposition from scoring.
Defenders fall into four main categories: centre-backs, full-backs, sweepers, and wing-backs. The centre-back and full-back positions are most common in modern formations. The sweeper and wing-back roles are more specialised, often limited to certain formations dependent on the manager's style of play and tactics.