A line in ice hockey is a term used to describe a group of forwards that play in a group, or shift, during a game. A complete forward line consists of a left wing, a center, and a right wing, while a pair of defensemen who play together are called a "defensive pairing." Typically, a team dresses twelve forwards along four lines and three pairs of defensemen, though some teams elect to dress a seventh defenseman. In ice hockey, players are substituted "on the fly," meaning there is no break in the action during the substitution of players. Usually, groups of players are substituted simultaneously in coordinated groups. This is referred to as a "line change." These players are called linemates. Linemates may change throughout the game at the coach's discretion.