The penalty kick rules were invented by the association of football (soccer) and is a type of free kick taken from 12 yards (11 meters) out from your opponent's goal with only the goalkeeper and you (the penalty taker).
If your opponent commits a foul punishable with a free kick within their own penalty area (also known as the box or the 18 yard box) or a handball your team will be awarded with a penalty kick.
I remember my first soccer match. My coach told me that I will play left back and said even "Whatever you do, don't commit a foul inside the 18 yard box."