A strategy that an offensive team will use in order to maximize the amount of yardage that a running back can gain on a carry. The offensive linemen will attempt to block the defensive players in directions that will create a lane of open field through which the running back can advance the ball. A running unit is much more effective if they can open up holes for the back, since the defense is not in a position to make a tackle near the line of scrimmage.
Most running plays are designed to open up a hole for the running back to advance through. After the snap the linemen will move to block the defensive players in a way that creates an open lane that the running back can go through. An effective running offense will be adept at opening holes on every play. The defense will attempt to combat the strategy by having players shed blocks to close the hole, or by having a linebacker or safety race through the hole to engage the running back.