Life
Life is the most important resource in the game. It represents your physical well-being. You lose Life when you are hit by attacks (weapons, spells, traps, etc.). If your Life drops below 0, you die (unless you are under the influence of something like a heroism infusion, allowing you to temporarily persist with negative Life).
Most characters regenerate Life each turn. The amount of Life regenerated depends on certain talents (such as Fast Metabolism) and equipment. Regeneration infusions can greatly boost Life regeneration for a short time.
Larger amounts of Life can be restored with various healing talents such as Healing Light and Nature's Touch. Many of these do not function on undead races.
The rate of Life regeneration accelerates each turn while resting (pressing the r key in the default bindings).