In gridiron football, a lineman is a player who specializes in play at the line of scrimmage. The linemen of the team currently in possession of the ball are the offensive line, while linemen on the opposing team are the defensive line. A number of NFL rules specifically address restrictions and requirements for the offensive line, whose job is to help protect the quarterback from getting sacked for a loss, or worse, fumbling. The defensive line is covered by the same rules that apply to all defensive players. Linemen are usually the largest players on the field in both height and weight, since their positions usually require less running and more strength than skill positions.
A linebacker is a playing position in gridiron football. Linebackers are members of the defensive team, and line up approximately three to five yards behind the line of scrimmage and behind the defensive linemen. They represent the "middle ground" of defenders, playing closer to the line of scrimmage than do the defensive backs, but farther back than do the defensive linemen.
In gridiron football, blitzing is a tactic used by the defense to disrupt pass attempts by the offense. During a blitz, a higher than usual number of defensive players will rush the opposing quarterback, in an attempt either to tackle him or force him to hurry his pass attempt.
Strategy forms a major part of American football. Both teams plan many aspects of their plays (offense) and response to plays (defense), such as what formations they take, who they put on the field, and the roles and instructions each player are given. Throughout a game, each team adapts to the other's apparent strengths and weaknesses, trying various approaches to outmaneuver or overpower their opponent in order to win the game.
American football positions have slowly evolved over the history of the sport. From its origins in early rugby football to the modern game, the names and roles of various positions have changed greatly, some positions no longer exist, and others have been created to fill new roles.
A formation in football refers to the position players line up in before the start of a down. There are both offensive and defensive formations and there are many formations in both categories. Sometimes, formations are referred to as packages.
In American football, a zone blitz is a defensive tactic that sends additional players to rush the opposing team's quarterback, whilst also unexpectedly redirecting a supposed pass rushing player into pass coverage instead. This tactic also likely includes zone coverage.
Single set back is an offensive base formation in American football which requires only one running back lined up about five yards behind the quarterback. There are many variations on single back formations including two tight ends and two wide receivers, one tight end/three wide receivers, etc. The running back can line up directly behind the quarterback or offset either the weak side or the strong side.
In American football, the specific role that a player takes on the field is referred to as their "position". Under the modern rules of American football, both teams are allowed 11 players on the field at one time and have "unlimited free substitutions", meaning that they may change any number of players during any "dead ball" situation. This has resulted in the development of three task-specific "platoons" of players within any single team: the offense, the defense, and the so-called 'special teams'. Within these three separate "platoons", various positions exist depending on the jobs that the players are doing.
Safety is a position in gridiron football on the defense. The safeties are defensive backs who line up ten to fifteen yards from the line of scrimmage. There are two variations of the position: the free safety and the strong safety. Their duties depend on the defensive scheme. The defensive responsibilities of the safety and cornerback usually involve pass coverage towards the middle and sidelines of the field. While American (11-player) formations generally use two safeties, Canadian (12-player) formations generally have one safety and two defensive halfbacks, a position not used in the American game.
There are several defensive formations commonly used in eight-man football. Defensive formations are classified by the total number of linemen and linebackers in the formation. The three basic types of formations in eight-man football are seven-man fronts, six-man fronts and five-man fronts.
In American football, a play is a close-to-the-ground plan of action or strategy used to move the ball down the field. A play begins at either the snap from the center or at kickoff. Most commonly, plays occur at the snap during a down. These plays range from basic to very intricate. Football players keep a record of these plays in a playbook.
In American football, the 3–4 defense is a common defensive alignment consisting of three down linemen and four linebackers. It is a called a "base defense" because it is the default defensive alignment used on "base downs". However, defenses will readily switch to other defensive alignments as circumstances change. Alternatively, some defenses use a 4–3 defense.
Zone coverage is a defense scheme in gridiron football used to protect against the pass.
In American football, a 4–3 defense is a defensive alignment consisting of four down linemen and three linebackers. It is called a "base defense" because it is the default defensive alignment used on "base downs". However, defenses will readily switch to other defensive alignments as circumstances change. Alternatively, some defenses use a 3–4 defense.
The following terms are used in American football, both conventional and indoor. Some of these terms are also in use in Canadian football; for a list of terms unique to that code, see Glossary of Canadian football.
In American football, the 4–4 defense is a defensive alignment consisting of four down linemen and four linebackers.
The 7–2–2 defense or seven-box defense, used seven "down linemen", or players on the line of scrimmage at the time of the snap, two linebackers, and two safeties. Amos Alonzo Stagg invented the seven-box defense in 1890 at Springfield College. At that time, most teams were using a nine-man line on defense, and there were only three downs and no forward passes. The 7–2–2 was the base defense used by Knute Rockne at Notre Dame, as well as Mike Donahue at Auburn. Into the late 1930s, the 7–2–2 was still commonly employed inside the defender's thirty-yard line. It was considered "very strong against a running attack, but rather weak defensively against passes." The 7–2–2 was also employed when the opponent was expected to punt.
The 7–1–2–1, or seven-diamond defense, used seven "down linemen", or players on the line of scrimmage at the time of the snap, one linebacker, two safeties relatively close to the line and one safety farther downfield. The formation was created by Minnesota Golden Gophers coach Henry L. Williams in 1903, reputedly to stop Michigan back Willie Heston. By some accounts in the mid-1930s, the 7–1–2–1 was considered "almost obsolete" due to its weakness against the forward pass, whereas the 7–2–2 defense was still considered viable. Yet Bill Arnsparger notes the use of the seven-diamond from the 1940s into the 1960s, as a defensive adjustment to the common wide tackle 6 defenses of the time. Further, the form of the 7 diamond as derived from a wide tackle 6, with a more compact line spacing than the 1930s era 7 man lines, shows a marked similarity to the 46 defense of Buddy Ryan.
