In sport (particularly football), a back is a player whose normal position is behind the forwards.

• In rugby union, this means a player who is not involved in the scrum
• In soccer it is another term for the position of defender
• In hockey and many other games it means a player who is defending the goal
• Back may be qualified by other terms:
  • Fullback, a common position in many football games
  • Quarterback, a position in the offensive backfield of American and Canadian football
  • Running back, a position in the offensive backfield of American and Canadian football

Sports terminology