In sports, a starting lineup is an official list of the set of players who will participate in the event when the game begins. The players in the starting lineup are commonly referred to as starters, whereas the others are substitutes or bench players.
The starters are commonly the best players on the team at their respective positions. Consequently, there is often a bit of prestige that is associated with being a starter. This is particularly true in sports with limited substitutions, like baseball or association football (soccer).
When listing a team's lineup, it is common in some sports to include each player's uniform number and their position, along with their name. Position are often designated by abbreviations that are specific to the sport (for example, in American football; "SS" for strong safety). In both baseball and basketball, it is common for a player's position to be denoted by a number, for example: in baseball scorekeeping the shortstop position is "6", while in basketball the small forward position is known as the "three". Thus, the lineups for some sports can include a uniform number, the player's name, and an abbreviation (consisting of letters or numbers) denoting a position.
American football
In American football since the 1950s, most upper level teams use a three-platoon system, each with its own starting lineup. The starting lineups for offense and defense, each with eleven players, typically get the most attention. The starting lineups are defined as the eleven players who take the first offensive or defensive play from scrimmage of a given game. (An offensive player does not have to be on the team that gets possession first to be considered a starter, nor does a defensive player have to be on the team that does not; the first play from scrimmage after the first change of possession counts as well.) The third platoon, special teams, in modern times is composed mostly of backup and reserve players from the offensive or defensive platoons, with the exception of the placekicker or punter; the players who, for instance, take part in the opening kickoff are typically not considered starters.
The player positions dictate certain responsibilities and privileges in regard to handling the ball. A uniform numbering system restricts players' ability to change positions in the middle of the game.