Health Points
Health Points (or HP) are a measure of a character’s very life force. Their decline could be due to all sorts of physical problems: injuries, disease, old scars, etc. Simply put, Health Points represent how much "life" the character still possesses. When health reaches zero, the character is dead.
A creature's size determines how many health points it has. Most characters starts out the game with 30 Health Points, so long as they're about human-sized. Damage in combat lessens the character's remaining HP. Like we said before, when a character reaches zero life, it's curtains, hear? Curtains! The Tempered trump allows you to increase your maximum HP.
For more information about how to lose or gain health, as well as the amount of HP granted to different sized creatures, see the Life and Death chapter.