<p>A halfback, sometimes referred to as a tailback, is an offensive position in American football, which lines up in the backfield and generally is responsible for carrying the ball on running plays. Historically, from the 1870s through the 1950s, the halfback position was both an offensive and defensive position. In the related sport of Canadian football, halfback is a defensive rather than offensive position.
Before the emergence of the T-formation in the 1940s, all members of the offensive backfield were legitimate threats to run or pass the ball. Most teams used four offensive backs on every play: a quarterback, two halfbacks, and a fullback. The quarterback began each play a quarter of the way back, the halfbacks began each play side by side and halfway back, and the fullback began each play the farthest back.
The sport's first triple threat, Bradbury Robinson of St. Louis University, ran, passed, received and punted out of the halfback position. It was as a halfback that Robinson threw the first legal forward pass to teammate Jack Schneider in a game at Carroll College on September 5, 1906.
Now that most offensive formations have only one or two running backs, the original</p>