The defender usually depends on the sport. In soccer (football) the defender is the one that protects the goal. I don't know much about football (American Football)
a defender stops the ball from going into the goal the defender stand in front of the goalkeeper and tackles
Any player, including defenders and goalkeepers, can score a goal in a game of football (soccer).
ON-SIDE in soccer or football is when a player from the attacking has one defender between him, the goalie and goal.
It is when a manchester united player shoots at the goal and a manchester city defender gets in the way
English football uses the offside rule where at least on defender has to be between the attacker and the goal.
how do you score a goal when the goal keeper is out of the box?
Defend
The goal keeper is always considered a defender, if he is in or out of the penalty area.
If a defender passes the ball with his feet to the goal keeper, the goal keeper may not touch the ball with their hands.
Defender
A football position