Gridiron position is a term used to describe the various roles that players take on in American football. The halfback is an offensive player who lines up behind the quarterback and is responsible for running, catching, and blocking. The cornerback is a defensive player who lines up on the outside of the field and is responsible for covering receivers. The END is an offensive player who lines up at the END of the line of scrimmage and is responsible for blocking and receiving passes. The tightend is an offensive player who lines up next to the tackle and is responsible for blocking and receiving passes. The left tackle is an offensive player who lines up on the left side of the line of scrimmage and is responsible for protecting the quarterback from opposing players. The linebacker is a defensive player who lines up behind the line of scrimmage and is responsible for defending against the run and the pass.