Defender (association football)
In the sport of association football, a defender is an outfield player whose primary role is to prevent the opposing team from scoring goals.
There are four types of defenders: centre-back, sweeper, full-back, and wing-back. The centre-back and full-back positions are essential in most modern formations. The sweeper and wing-back roles are more specialised for certain formations.
A centre-back (also known as a central defender or centre-half) defends in the area directly in front of the goal, and tries to prevent opposing players, particularly centre-forwards, from scoring. Centre-backs accomplish this by blocking shots, tackling, intercepting passes, contesting headers and marking forwards to discourage the opposing team from passing to them.
With the ball, centre-backs are generally expected to make short and simple passes to their teammates, or to kick unaimed long balls down the field. For example, a clearance is a long unaimed kick intended to move the ball as far as possible from the defender's goal.