Man-to-man defense, man defense, man-on-man defense, or player-on-player defense, is a type of defensive system used in team sports such as American football, association football, Australian rules football, basketball and netball, as in which each player is assigned to defend and follow the movements of a single player on offense. Often, a player guards his counterpart, but a player may be assigned to guard a different position. However, the strategy is not rigid, and a player might switch assignment if needed, or leave his own assignment for a moment to double-team an offensive player. The term is commonly used in both men's and women's sports. The alternative to man-to-man defense is zone defense, a system of defense in which each player guards an assigned area rather than a specified opponent.