The players and coaches

Every football team has some players who play offense and others who play defense. Before each play, the offensive and defensive teams face each other along the line of scrimmage. This imaginary line aligns with the spot where the preceding play ended. The line of scrimmage parallels the yard lines and passes through the tip of the ball nearest each team's goal. Thus, each team has its own line of scrimmage, separated by the length of the football. The area between the two lines is called the neutral zone.

The offensive team consists of seven linemen and four backs. The team must have at least seven players on the line of scrimmage before a play. The linemen are divided into five interior linemen and two ends. The interior linemen consist of a center, two guards, and two tackles. They block for the ball carriers, passers, and pass receivers. The center also snaps (gives) the ball through his legs to the quarterback to begin a play.

Each of the two ends plays a position on the outside of the interior linemen. Ends may receive passes. Many offensive formations (arrangements of players) have two types of ends: (1) the tight end and (2) the split end, or wide receiver. The tight end lines up near the tackle. Although the tight end is a pass receiver, he also has important blocking responsibilities. The split end lines up opposite the tight end and several yards from the tackle. The split end is used mainly as a pass receiver.

The four backs make up the backfield, which generally consists of a quarterback, two halfbacks, and a fullback. In the standard T-formation, the fullback lines up 3 to 5 yards behind the quarterback and has a halfback on each side. The backs also have other names. A fullback used chiefly as a blocker is a blocking back. A halfback who lines up outside the tight end is called a flanker or a wingback. A halfback who usually carries the ball is a running back.

Most interior linemen are bigger and stronger than backs and ends because they must block against large defensive linemen. Most backs and pass receivers are smaller than linemen but faster and more agile.

The defensive team is divided into three units: (1) the line, (2) the linebackers, and (3) the secondary.

The line may have as many players as the defensive team chooses. But most teams use three, four, or five players. A three-man line consists of a middle guard, also called a nose guard, and two ends. A four-man line, called the front four, consists of two tackles and two ends. A five-man line consists of a middle guard, two tackles, and two ends. The defensive linemen use their size, strength, and power against offensive blockers.

The linebackers position themselves 2 or 3 yards behind the linemen. A team that uses a four-man line will normally have three linebackers. The player who lines up facing the center is the middle linebacker. The two other players, called outside linebackers, stand outside the defensive ends. Four linebackers are used with a three-man line, and two are used with a five-man line. In certain defensive formations, the linebackers will move up to the line of scrimmage with the linemen.

Linebackers, especially middle linebackers, make many tackles. They must combine strength with the ability to move quickly to wherever the ball carrier is running. They must also be good pass defenders.

The secondary is made up of two cornerbacks and two safeties. They are often called defensive backs. Their chief task is to defend against the offensive team's passing attacks. They also try to tackle ball carriers who have gotten by the linemen and linebackers. Defensive backs must be fast enough to cover speedy pass receivers, and they must be especially sure tacklers.

The cornerbacks stand 8 to 10 yards behind the line of scrimmage at the corners of the defensive formation. They defend against short passes thrown toward the sidelines. Safeties play 8 to 12 yards behind the line of scrimmage and defend against long passes. Sometimes, secondaries use double coverage, in which two defensive backs cover an especially dangerous receiver.

Many defensive teams favor zone coverage in the secondary, and others prefer man-to-man coverage. In zone coverage, each defensive back is responsible for a certain area. In man-to-man coverage, a defensive back is assigned to cover a particular receiver.

The coaches. Every team has a coaching staff made up of a head coach and a number of assistant coaches. The head coach decides which players play which positions and, often, what plays are used during a game. Most assistant coaches work with particular players on the offensive and defensive teams. Some assistant coaches may perform other duties, such as scouting opposing teams for their strengths and weaknesses.

Between games, the coaches conduct practices to correct players' mistakes and to oversee their physical conditioning. The coaches also prepare for the next game by developing a game plan. A game plan is a list of offensive plays and defensive formations that the coaches believe will work against the opponent. Some coaches discuss the game plan with the quarterback and then allow him to select his own plays during the game. Other coaches prefer to choose the plays themselves. During a game, they send in their instructions for each play with a substitute player.