Football is a game played between two teams of players.
Too Many Players
At this point, you might be confused. Why does a football team have 53 players on its roster if only 11 players can be on the field playing? The reason is because football allows for unlimited substitutions.
Football is different from other sports in that it allows for unlimited substitutions in between plays. At any point, a team can substitute the 11 players on the field for a new set of 11 players.
Since football allows for unlimited substitutions, players are highly specialized in their roles on the field. As a result, players are grouped into three main categories or units: