Constitution

 is an ability score in Pathfinder.

Description
Constitution represents your character's health and stamina. A higher Constitution increases a character's Hit Points, so the ability is important for all classes. Some creatures, such as undead and constructs, do not have a Constitution score. Their modifier is +0 for any Constitution-based checks. If a character's Constitution falls to 0, the character dies.

You apply your character's Constitution modifier to:

-Hit points gained each level. If a character's Constitution score changes enough to alter his or her Constitution modifier, the character's hit points also increase or decrease accordingly. (Note that Constitution penalties can never drop the result below 1. Thus, a character always gains at least 1 hit point each time he advances in level.)

-Fortitude saving throws for resisting poison, disease, and similar threats.

Characters die when their current hit points equal a negative value equal to their constitution score.