Heart Point
HP is a term used in each of the Mario Role Playing Games, and many other RPGs as well. It stands for Health Points (and Hit Points sometimes) and means just as its name suggests. It can be filled using health Items like Mushrooms as well as Heart Blocks (from Paper Mario: The Thousand-Year Door). It is often a number counter. If it reaches zero, Mario will be KOed and the player will receive a Game Over unless he or she has a Life Shroom in stock.
To decrease the chance of this happening, Mario can choose to increase his maximum HP when leveling up.
In Super Paper Mario, some enemies' HP is listed as "??". This means that the enemy is always defeated with either a set amount of stomps or a special manuver, no matter how much HP the enemy attains upon doing so.
