Football is a team sport played in a large field with a ball that is kicked, thrown, and passed. There are 11 players on each team who participate in all phases of play, but the most important position is quarterback, or the person who calls the plays from the center and hands the ball off to the running backs and wide receivers. The quarterback is a key part of the offense, but they also help with defense as well. Each team has a quarterback coach who helps the player develop his skills.
The game begins with a kickoff, when one team, called the kicking team, kicks the ball to another team, called the receiving team. The receiving team then tries to get the ball past the line of scrimmage and into its end zone, or scoring area. This is done by either running with the ball and trying to get into the end zone, or passing the ball to a teammate who can then run into the end zone for a touchdown. There are also two-point conversions which can be attempted after a touchdown by kicking the ball through the goal posts.
During each down of the game, the offensive team has four chances to advance the ball 10 yards. There are markers placed on the field to show how close a team is to getting to the end zone. If the team does not make it in this time, they must turn over the ball to the other team. The other team then tries to prevent the other team from scoring, which may include stopping the running back or passing the ball to a player who can be tackled before reaching the end zone.
There are many rules governing the game of football to ensure that all players and teams are treated fairly and safely. The players are constantly looking for ways to gain an advantage over their opponents, so there is a system of penalties and fouls in place to try to limit this.
Teams change ends of the field at the end of the first and third quarters, but otherwise the situation on the field with respect to possession, downs remaining, and distance to goal does not change between periods. However, if a runner goes out of bounds — that is, any part of his body — on or past the sidelines or end zone, then that down must be replayed.
The offensive team arranges itself in a specific formation behind its own line of scrimmage, and only seven players on that team can touch the ball during each play. The other players are considered to be out of bounds if they touch the ground or any other object outside the playing area. The defensive team is trying to stop the ball-carrier and can tackle, or throw down, the runner, or push him into out of bounds. This is not uncommon, since the running game of football is a fast and physical one.