A penalty kick is awarded when a defender, while within his own penalty area, commits a penal foul (normally punishable by a Direct Free Kick) against an attacker or against the Spirit of the Game.
There are 10 penal fouls that are punishable by a direct free kick:
- kicks or attempts to kick an opponent
- trips or attempts to trip an opponent
- jumps at an opponent
- charges an opponent
- strikes or attempts to strike an opponent
- pushes an opponent
- tackles an opponent
- holds an opponent
- spits at an opponent
- handles the ball deliberately (except for the goalkeeper within his own penalty area)
If any of these are committed, against an attacker, by a defender while the ball is in play and while inside the defender's penalty area, then a penalty kick is awarded to the attacking team.
Note that there could also be misconduct resulting in a caution or a send off, but that uses a different set of criteria and is not automatic.