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, behind the defensive linemen, and therefore "back up the line". The different responsibilities of outside linebackers in the 3-4 and 4-3 defenses usually lead to very different skill sets and body types being sought out by teams as to best fit their particular defenses, 3-4 OLB's are generally, or primarily required to play North to South, are lankier/taller, bulkier and stronger/more powerful as to effectively aid the ends in setting the edge on running plays and provide pressure to the Quarterback on passing plays, and will usually have an arsenal of pass rush moves used primarily against the blockers the offense has on the edge of their line. 4-3 OLB's generally are expected to more proficiently move East to West more often and therefore are usually rangier players more adapt in covering potential receiving targets off the line or from the backfield, as well as having outside contain beyond the tackle box on run plays. Linebackers generally align themselves before the ball is snapped by standing upright in a "two-point stance".