Editing Cornerback (section)

== Overview ==
The cornerback's chief responsibility is to defend against the offense's pass. The rules of [[American football|American professional football]] and American [[college football]]  do not mandate starting position, movement, or coverage zones for any member of the defense.<ref>{{Cite web| title = NFL Rules Digest: Position of Players at Snap| website = [[NFL.com]]| url = http://www.nfl.com/rulebook/positionofplayers| access-date = January 7, 2010}}</ref><ref>{{Cite web |title=2009-10 NCAA Football Rules and Interpretations |date=May 2009 |publisher=[[National Collegiate Athletic Association]] |url=https://www.ncaapublications.com/productdownloads/FR09.pdf |access-date=February 8, 2024}}</ref> There are no "illegal defense" formations. Cornerbacks can be anywhere on the defensive side of the [[line of scrimmage]] at the start of play, although their proximity, formations, and strategies are outlined by the coaching staff or captain. Examples of cornerbacks in the NFL are [[Jalen Ramsey]], [[Patrick Surtain II]], [[Marlon Humphrey]], [[Jaire Alexander]], [[Sauce Gardner]], [[L'Jarius Sneed]], and [[Charvarius Ward]].

[[File:Cornerback.JPG|thumb|alt=Two football players, an offensive receiver and a defensive cornerback, both reach for a thrown football. The cornerback is in front of the receiver with the ball almost secured in his hands.|A cornerback for [[Dublin University American Football Club|Trinity College]] rises to [[Interception#American/Canadian football|intercept]] a pass]]

Most modern [[National Football League]] defensive formations use four defensive backs (two safeties and two corners); [[Canadian Football League]] defenses generally use five defensive backs (one [[Safety (American football position)|safety]], two defensive [[Halfback (Canadian football)|halfbacks]], and two corners). A cornerback's responsibilities vary depending on how the defense assigns protection to its defensive secondary. In terms of defending the run, often corners may be assigned to blitz depending on the coaching decisions in a game. In terms of defending passing plays, a corner will be typically assigned to either zone or man-to-man coverage.

The most effective cornerbacks are typically called "lockdown corners". These elite defenders cover an offensive receiver so effectively on either side of the field that the quarterback does not target the receiver being covered.

===Zone===
In [[Zone defense in American football|zone coverage]], the cornerback defends an assigned area of the field. Many schemes and variations were created to provide defensive coordinators great latitude and flexibility which aim to thwart offensive schemes.

When a team is using [[zone coverage]], some areas of the field require special attention when defending against specific pass plays. They include the flats (to defend the screen pass and hitch routes), mid range zones including the void (to defend the "stop n go", quick post, fade, hook, curl, and "sideline" or "out" routes), and finally the deep zones (to defend the post/deep post, chair, streak, "fly", "go", bomb, or [[Hail Mary pass|Hail Mary]] routes). These are basic terms (perhaps the most generic) for the basic zones and routes which vary system to system, league to league, and team to team.

Advanced forms of coverage may involve "quarterback spies" and "containment" coverages, as well as various "on field adjustments" that require shifts and rotations; the latter usually initiated by the captain of the secondary (typically the [[free safety]]) during the quarterback's cadence.  At this time the captain attempts to "read" the alignment (pro set, split set, trips, etc.) of the offensive "skill players" (backs and receivers) in order to best predict and counter the play the offense will run. He will base his decision on past experience, game preparation, and a sound comprehension of his teammates strengths, abilities, and tendencies. These adjustments may change on a play by play basis, due to substitutions or even evolving weather or field conditions. For example, defensive coordinators may favor a tendency to play a less aggressive containment style zone coverage during wet or slippery field conditions to avoid problems associated with over-pursuit (when a defender takes a poor angle on a ball carrier and cannot redirect in time due to poor footing).

===Cover 1===
The Cover 1 defense is an aggressive formation employed against offenses trying to gain short yardage. In the Cover 1 defense, one defender—normally a safety—plays deep zone downfield, providing security over the top and freeing the other safety to rush the line of scrimmage or drop back into coverage. Meanwhile, the corner's primary responsibility is to play on or off the receiver and not release him vertically. Defensive coordinators typically call for Cover 1 formations only when their cornerbacks are skilled at playing man-to-man coverage.

===Cover 2===
The [[Cover 2]] formation, which deploys four defensive backs in a "two-deep zone", is popular among NFL defensive coordinators because it uses two safeties to defend the deep routes instead of one. The safeties line up on or near their respective hashmarks between 11 and 15 yards off the line of scrimmage, while the cornerbacks line up around five yards from the wide receivers nearest to each sideline. With the safeties able to watch the play develop in front of them, the corners are free to pursue a more aggressive style of play.

In Cover 2, the cornerback is usually responsible for "containment", meaning that he is tasked with preventing any eligible receiver or ball carrier from running between him and the sideline. He funnels receivers toward the middle of the field and may physically "jam" them within five yards of the line of scrimmage in order to disrupt their assigned routes. If he determines that the offense is not attempting a running play or a pass into the flat, he then drops back to defend the secondary. This is often referred to as the "catch-and-run" technique.  Typically, cornerbacks mirror each other's zone responsibilities. However, sometimes they play a "man-up" style of [[bump and run coverage|bump-and-run]] coverage designed to eliminate the short pass, where the receiver is forced to the near sideline, which is the opposite of the run-oriented "containment" style of Cover 2.

===Cover 3===
In a "Cover 3", the two corners and [[free safety]] defend their assigned deep thirds of the field, where the corners defend the outside thirds, (hence the term corner) while the safety defends the middle third. This allows the strong safety to address a full range of duties depending on what reads he makes coupled with the coverage called. These duties may simply include single or zone coverage, being a quarterback spy, providing extra run support in short yardage situations, or to stunt or blitz through a gap or from the end.

===Cover 4===
In a "Cover 4" each defensive back is responsible for covering his designated "deep fourth" of the field, while other defensive players are responsible for covering the underneath areas. Sometimes Cover 4 is used as a "prevent defense".

Variations of these coverages exist to counter the many styles of offenses a defense may face on any given week. For example, one variation of the Cover 2 allocates the weak-side corner (e.g.: typically the "right cornerback" when playing against right-handed quarterbacks) to cover half the field in order to free up a safety; the idea being to allow the safety to engage a different part of the field, blitz, contain, or spy.  The strong side cornerback (the "left cornerback") may be in a variety of different alignments which may include "loose man", "man-under", or "man-up". Although these are forms of single coverage, more often than not his responsibility is usually limited to an initial jam and funnel with a subsequent drop back into  the "void". This pie-shaped slice of field is included with your most basic 2 Deep Zone coverage. One interesting aspect sometimes encountered with Cover 2 is that it is possible for one corner to be in a zone coverage, where he funnels and drops into the void, while another may be in man coverage. However, your basic garden variety 2 Deep Zone usually employs the two safeties to share half the field responsibilities, with the two corners funneling.