A running back (RB) is a member of the offensive backfield in gridiron football. The primary roles of a running back are to receive handoffs from the quarterback to rush the ball, to line up as a receiver to catch the ball, and block. There are usually one or two running backs on the field for a given play, depending on the offensive formation. A running back may be a halfback, a wingback or a fullback. A running back will sometimes be called a "feature back" if he is the team's key player/more prominent running back.
Zamir White, a running back then playing at the collegiate level for the Georgia Bulldogs during a game versus the South Carolina Gamecocks.
A running back turns up the field in an attempt to reach the end zone.
Darren Sproles, a "scat back"
Adrian Peterson and Christian McCaffrey representing an old school and modern running backs styles respectively.
The offensive backfield is an ambiguous generic term of football, which includes: (1) a place, namely the area of an American football field behind the line of scrimmage; and (2) a group classification of certain players positioned there, i.e., members of offense who begin plays behind the line, typically including any backs on the field, such as the quarterback, halfbacks and fullback. There are rules specific to the manner of play in that area.
1917 Georgia Tech backfield