American football positions
In American football, the specific role that a player takes on the field is referred to as their "position." Under the modern rules of American football, both teams are allowed 11 players on the field at one time and have "unlimited free substitutions," meaning that they may change any number of players during any "dead ball" situation. This has resulted in the development of three task-specific "platoons" of players within any single team: the offense (the team with possession of the ball, which is trying to score), the defense (the team trying to prevent the other team from scoring, and to take the ball from them), and the so-called 'special teams' (who play in all kicking situations). Within these three separate "platoons", various positions exist depending on the jobs that the players are doing.