backfield
The football players lined up behind the line of scrimmage.
In football, the backfield refers to the area behind the line of scrimmage and the players positioned there.
When the offense lines up for a play, some players start right at the line where the ball sits (the linemen), while others stand several yards back. These players standing back from the line make up the backfield. On most plays, the backfield includes the quarterback and the running backs. The quarterback takes the snap and decides whether to hand off to a running back, throw a pass, or run with the ball.
The backfield is where much of the action starts. Running backs use this space to build up speed before hitting the line, and quarterbacks need room to drop back and scan the field for open receivers. A strong backfield with talented running backs and a skilled quarterback makes an offense much harder to defend against.
You might hear announcers say a team has “depth in the backfield,” meaning they have several good players who can carry or catch the ball.