Each team has eleven players on the field at any one time, although football teams can have as many as 50 players. Specialised offensive, defensive and specialist players are employed by each team, and are brought onto the field for a particular play.

Before the beginning of each game, the referee tosses a coin to determine which team will be given the choice of taking first possession of the ball or choosing which end of the field will be their end-zone for the first half. It is unusual for a team not to choose first possession of the ball. After half-time, the team which lost the toss will be given possession of the ball (assuming that they were not awarded it by the opposing team in the first half).

At the end of the first and third quarters, the teams switch ends to equalise any advantages or disadvantages associated with either end of the field.

Each team is entitled to three ‘time-outs’ for every half. During a time-out, team mates discuss their strategy for their next plays. These are usually worked out and practised before the game and there will usually be a verbal signal, typically shouted out by the quarterback, so that players know when to act.

Games last for one hour, and this time is divided up into four fifteen minute quarters. In practice, however, a game will last for around three hours, as the clock is stopped when the offensive team runs a passing play and pass is not completed, the player carries the ball out of bounds and during time-outs. Half-time lasts for twelve minutes and is held after the second quarter.