The Football Players: Each football team has 3 separate units: the offense, those players who are on the field when the team has possession of the ball; the defense, players who line up to stop the other team's offense; and special teams that only come in on kicking situations (punts, field goals, and kickoffs). Only 11 football players are on the field from one team at any one time.
The Kickoff: A football game starts with the kickoff. The ball is placed on a kicking tee at the defense's 30-yard line, and a special kicker (a "placekicker") kicks the ball to the offense. A kick return man from the offense will try to catch the ball and advance it by running. Where he is stopped is the point from which the offense will begin its drive, or series of offensive plays. When a kickoff is caught in the offense's own end zone, the kick returner can either run the ball out of the end zone, or kneel in the end zone to signal a touchback - a sign to stop the play. The ball is then placed on the 20-yard line, where the offense begins play.
First Down: All progress in a football game is measured in yards. The offensive team tries to get as much "yardage", as it can, to try and move closer to the opponent's end zone. Each time the offense gets the ball, it has four downs, or chances, in which to gain 10 yards. If the offensive team successfully moves the ball 10 or more yards, it earns a first down, and another set of four downs. If the offense fails to gain 10 yards, it loses possession of the ball. The defense tries to prevent the offense not only from scoring, but also from gaining the 10 yards needed for a first down. If the offense reaches fourth down, it usually punts the ball (kicks it away). This forces the other team to begin its drive further down the field.
Moving the Football: A football play begins with the snap. At the line of scrimmage (the position on the field where the play begins), the quarterback loudly calls out a play in code and the football player in front of him, the center, passes, or snaps the ball under his legs to the quarterback. From there, the quarterback can either throw the ball, hand it off, or run with it.
The Run: There are two main ways for the offense to advance the ball. The first is called a run. This occurs when the quarterback hands the ball off to a running back, who then tries to gain as many yards as possible by eluding defensive players. The quarterback is also allowed to run with the ball.
The Pass: The other alternative to running the ball is to throw it. Or as they say in football, pass it! Usually, the quarterback does the passing, though there are times when another football player may pass the ball to confuse the defense. Actually, anyone on the offensive team is allowed to pass the ball as long as the pass is thrown from behind the line of scrimmage. A pass is complete if the ball is caught by another offensive player, usually the "wide receiver" or "tight end." If the ball hits the ground before someone catches it, it is called an incomplete pass.
The Tackle: The defense prevents the offense from advancing the ball by bringing the ball carrier to the ground. A player is tackled when one or both of his knees touch the ground. The play is then over. A football play also ends when a player runs out of bounds.
