Defensive Formation – 4-3 Defense Diagram

"In American football, a T formation (frequently called the full house formation in modern usage) is a formation used by the offensive team in which three running backs line up in a row about five yards behind the quarterback, forming the shape of a "T".
Numerous variations of the T formation have been developed, including the Power-T, where two tight ends are used, the Pro T, which uses one tight end and one wide receiver, or the Wing T, where one of the running backs (or wingback) lines up one step behind and to the side of the tight end. Any of these can be run using the original spacing, which produced a front of about seven yards, or the Split-T spacing, where the linemen were farther apart and the total length of the line was from 10-16 yards." [T formation. Wikipedia]
The American football positions diagram example "Offensive formation - T-formation" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Football solution from the Sport area of ConceptDraw Solution Park.

"In American football, the pro set or split backs formation is a formation that was commonly used as a "base" set by professional and amateur teams. The "pro set" formation featured a backfield that deployed two running backs aligned side-by-side instead of one in front of the other as in traditional I-formation sets. It was an outgrowth of the original, three running back T-formation, with the third back (one of the halfbacks) in the T becoming a permanent flanker, now referred to as a wide receiver. ...
A common variant of this formation removes the tight end and replaces it with a third receiver in the "slot" position. The formation is utilized to remove a defensive player from the tackle box to give the offense a 7-on-6 matchup.
There are three formations in the pro set of forms: Pro, Ace, and Tree." [Pro set. Wikipedia]
The American football positions diagram example "Pro set formation (Offense)" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Football solution from the Sport area of ConceptDraw Solution Park.

"This base defense consists of four defensive linemen, three linebackers, and four defensive backs (two safeties, two corners). Against two-receiver offensive sets, this formation is effective against the run and the pass. In the original 4–3, defensive tackles would line up opposite the offensive guards, and defensive ends on the outside shoulders of the offensive tackles. On passing downs, the Mike (middle linebacker) is often responsible to cover any running backs, the Sam (strong-side linebacker) covers the Tight End, and the Will (weak-side linebacker) either covers a back or blitzes in an attempt to sack the quarterback. Though first used as a base defense by the New York Giants in 1956, plenty of teams experimented with it during the 1950s, and thus there are multiple claimed inventors of this defense. There are several different variations of the 4–3 defense such as the 4-3 under defense, 4-3 over defense, 4-3 umbrella defense, 4-3 swim defense, and 4-3 slide defense." [List of formations in American football. Wikipedia]
This example diagram was redesigned from the Wikimedia Commons file: 4-3 green.svg.
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This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. [creativecommons.org/ licenses/ by-sa/ 3.0/ deed.en]
The American football positions diagram example "Defensive Formation - 4-3 defense" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Football solution from the Sport area of ConceptDraw Solution Park.

"The shotgun formation is a formation used by the offensive team in American and Canadian football. This formation is used mainly for passing plays, although some teams use it as their base formation. In the shotgun, instead of the quarterback receiving the snap from center at the line of scrimmage, he stands farther behind the line of scrimmage, often five to seven yards back. Sometimes the quarterback will have a back on one or both sides before the snap, while other times he will be the lone player in the backfield with everyone spread out as receivers." [Shotgun formation. Wikipedia]
The American football positions diagram example "Shotgun formation (Offense)" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Football solution from the Sport area of ConceptDraw Solution Park.

"The goal line is the chalked or painted line dividing the end zone from the field of play in American football and Canadian football. It is the line that must be crossed in order to score a touchdown
If any part of the ball reaches any part of the imaginary vertical plane transected by this line while in-bounds and in possession of a player whose team is striving toward that end of the field, this is considered a touchdown and scores six points for the team whose player has advanced the ball to, or recovered the ball in, this position. This is in contrast with other sports like Association football and ice hockey, which require the puck or ball to pass completely over the goal line to count as a score.
If any member of the offensive team is downed while in possession of the ball behind his own team's goal line, this is called a safety and scores two points for the defensive team.
If, during the course of play, a loose ball travels past the goal line and is recovered within the end zone, then it is a touchdown if recovered by the kicking team, or a touchback if recovered and downed by the receiving team.
In the event of a kick recovered in one's own end zone, the entirety of the ball must pass the goal line in order for the ball to be considered in the field of play, and not a touchback." [Goal line (gridiron football). Wikipedia]
The American football positions diagram example "Goal line formation (Offense/ Defense)" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Football solution from the Sport area of ConceptDraw Solution Park.

"In American football, the dime defense is a defensive alignment that uses six defensive backs. It is usually employed in obvious passing situations.
The formation usually consists of six defensive backs, usually two safeties and four cornerbacks, and has either four down linemen and one linebacker, or three down linemen and two linebackers. This formation is to prevent the offense from completing a medium to long range pass play. This may be because the offense's running game is inefficient, time is an issue, or they need a long pass for a first down. It is also used against teams whose pass to run ratio predominately favors pass . The formation, however, is vulnerable to running plays as the formation is missing two linebackers, or a linebacker and a down lineman. A dime defense differs from the nickel in that it adds a sixth defensive back to the secondary. This sixth defensive back is called a "dimeback" (D). The defense gets its name because a dime is the next step up in US coin currency from a nickel. There are also 'quarter" and "half-dollar" formations (each protecting against progressively deeper thrown and more likely pass attempts)." [Dime defense. Wikipedia]
The American football positions diagram example "Dime defense" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Football solution from the Sport area of ConceptDraw Solution Park.