A football team roster is a running list of all active and inactive players on a team. It is utilized by coaches and officials throughout the entire season. It consists of the player's information, jersey number and any relevant statistical information, like game percentages, weight, height, etc.
Football players are grouped into three main groups on the roster:
Only 11 players from the active roster can be on the field of play during a scrimmage down. A penalty call, "Too Many Men on the Field" will be called on a team that has more than 11 players on the field.
Football allows unlimited substitutions during a game. Teams can substitute all 11 players on the field for a new set of 11 players when the ball is dead. They also can substitute individual players, too. Any member from the active roster may be substituted in at any point during the game.
Coaches will bring different players from their offense, defense, or special teams onto the field during different times in a football game if they want to do substitutions.