position. The third line is often called the checking line, and is generally made up of more defensively oriented forwards and grinders. This line is often played against an opponent's first or second lines in an effort to reduce their scoring, and physically wear them down. The third line adds less offense than the first or second lines, but generally more than the fourth. The fourth line is often called the "energy line," both because their shifts give other players a chance to rest, and because their physically oriented play is said to give their teammates an emotional boost. Traditionally it was composed of journeymen with limited scoring potential, but strong physical play and, as often as possible, strong skating abilities. With the smallest amount of ice time, they tend to play in short bursts rather than pace themselves. Pests and enforcers usually play the fourth line, as do centers whose primary skill is winning faceoffs. The fourth line can be a checking line. With the rise of analytics the traditional fourth line of enforcers is being replaced by more skilled players. Defense Defensemen operate in pairs rather than trios. The top pairing consists of the two strongest defenders on the team, and may play up to 30 minutes per game. Offensive defensemen may be placed on any pairing, while "stay-at-home" defenders typically play on the third pair. Coaches may also choose to pair a more offensively-minded defender with a more defensive player. Special teams A penalty kill unit is a specialized group of four or three players employed when a team is shorthanded due to a penalty. As the name describes, this is a primarily defensive unit meant to prevent the opposing team from scoring during their power play. A power play unit is a specialized group of five or four players when the opposing team has been called for a penalty and is shorthanded. This unit is a primarily offensive group of players meant to take advantage of scoring against the shorthanded opposing team. See also List of ice hockey linemates Goal line (ice hockey) Hockey rink References < Ice hockey terminology