Defensive lineman In American 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 . 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 position s . Offensive line . The interior offensive line consists of the center , who is responsible for snapping the ball into play , two guards who flank the center , and two offensive tackle s who flank the guards ; NFL rules require that a team have all five of these interior linemen on the field for every offensive play . In addition to the interior line , a full offensive line may also include a tight end outside one or both of the tackles . Interior offensive linemen are not eligible to catch forward passes , and are not allowed to have advanced past the line of scrimmage at the time a pass is thrown unless they are in contact with a defensive player . However , tight ends are eligible to catch passes . On running plays , the primary job of the offensive line is to create space for the ball carrier to run , either by pushing all defensive players backwards past the line of scrimmage , or by pushing defensive players to the side to allow the ball carrier to run past them . On some running plays , an offensive lineman will pull by backing out of his initial position and running behind the other offensive linemen to engage a defensive player beyond the initial width of the offensive line ; in modern games this duty usually falls to guards . On passing plays the offensive line is responsible for stopping defensive players from tackling the quarterback before he has thrown the ball . Stopping these players indefinitely is usually not possible , so the main objective of the offensive line is to slow them down , providing the quarterback with several seconds to identify an open receiver and throw the ball . An offensive lineman ' s motion during a play is often limited to just a few quick steps to establish position , followed by a wrestling match similar to sumo . Offensive linemen thus tend to be the largest players on the field , with excellent agility and balance but limited straight - line running speed . When an offensive linemen knocks a player down on a block without falling down themselves , it is often known as a pancake block . Defensive line . The defensive line consists of one or two defensive tackles and two defensive ends who play outside the defensive tackles . The defensive line works with the linebackers to try to control the line of scrimmage . The 4 - 3 defensive formation , most commonly used in the NFL , employs two defensive tackles ( and a defensive line of four men , with three linebackers behind them ) , while the 3 - 4 formation uses just a single defensive tackle , called the nose tackle ( and a defensive line of three men , with four linebackers behind them ) . However , defensive ends in a typical 3 - 4 have responsibilities more similar to a 4 - 3 defensive tackle than 4 - 3 defensive ends . On running plays , the goal is to tackle the ball carrier . The defensive line attempts to maintain their original formation ( even spacing without holes ) , but also to prevent any members of the opposing offensive line from successfully engaging the linebackers , who chase down the ball carrier . The defensive tackles are usually the most skilled run defenders on the team . On passing plays , the defensive line tries to reach the quarterback . Ideally , the defensive players are able to tackle the quarterback for a loss ( a sack ) , but in practice the quarterback will usually manage to throw the ball before an actual tackle is made ; the goal is thus to put pressure on the quarterback as quickly as possible to force him to throw the ball before he can find an open receiver . Defensive ends are usually the most skilled pass rushers on the team . In order to increase the pressure on the quarterback , teams will often have players other than the defensive line attempt to tackle the quarterback ; this is called a blitz . Because the defense does not know whether the offense is attempting to run a passing play or a running play ( or whether a quarterback will give up on an attempt to pass and instead run with the ball ) , they must balance passing and running strategies : running around offensive linemen and avoiding contact may allow faster pressure on a quarterback , but it also leaves a hole in the defensive line and frees an offensive lineman to engage a linebacker , enabling a big running play . Defensive linemen - - particularly defensive ends - - are called upon to do more running than offensive linemen , thus they usually tend to be somewhat smaller and faster .