Defensive fronts
3-4 front
Three down linemen and four linebackers, with pressure coming from the outside backers.
A 3-4 front uses three down linemen to occupy blockers and four linebackers behind them. Pressure comes from the outside backers, and the offense cannot tell before the snap which of the four is rushing.
The trade-off is that the three linemen must hold up against double teams for the structure to work.