In ice hockey, a line is 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 "partners." Typically, an NHL team dresses twelve forwards along four lines and three pairs of defensemen, though some teams elect to dress a seventh defenseman, or a thirteenth forward. In ice hockey, players are substituted "on the fly," meaning a substitution can occur even in the middle of play as long as proper protocol is followed (under typical ice hockey rules, the substituting player cannot enter the ice until the substituted player is within a short distance of the bench and not actively playing the puck); substitutions can still be made during stoppages. Usually, coordinated groups of players (called linemates) are substituted simultaneously in what are called line changes. Linemates may change throughout the game at the coach's say. Ice hockey is one of only a handful of sports (gridiron football and basketball being the two most prominent others) that allows for unlimited free substitution and uses a system of multiple sets of players for different situations. Because of the use of lines in hockey, ice hockey teams have relatively large rosters compared to the number of players on the ice (23 for a typical NHL team, with 20 active on game day and six on the ice at any given time). Only gridiron football has a larger relative roster size (the NFL has 53 players, 46 active on gameday, 11 on the field). Types of line Forward The first line is usually composed of the best offensive players on the team. Teams rely heavily on this line, which generates the bulk of the team's scoring. These players often see the highest number of minutes among forwards in a game and are usually part of the team's starting lineup. The second line is generally composed of second-tier offensive players, and helps by adding supplementary offense to that generated by the first line while contributing more two-way play than the offensively-focused scoring line. Higher end (typically first line) players may be put on the second line to spread scoring across the lineup, making a team more difficult for opponents to defend against. This frequently happens when a team has two high-end players who play the same