What is a nose guard in football?

In football, the nose guard is a defensive player who plays the middle position when there are three players on the defensive line. The position may also be called the nose tackle and is common in 3-4 defensive schemes.

Most of the time, the nose guard lines up directly across from the offensive center. The nose guard is often blocked by at least two different offensive linemen, sometimes by design, because by occupying multiple blockers, other players are free to make the tackle. Due to the difficulty of the position, the nose tackle is usually the biggest defensive player on the team.