Hit Points
Hit Points are a measurement of the amount of damage a unit can suffer before being killed. They are commonly referred to as Life, HP, or Health.
During a battle, an attacking stack of units subract their modified attack power from an enemy unit's hit points. The amount of units killed in an attack is the damage dealt divided by the hit point total of a unit within that stack. A partially damaged unit's current hit points is tracked throughout the battle, but healed to full at the battle's end.
For example, a flight of Chimera inflict 4830 points of damage onto a stack of Faerie Dragons. Faerie Dragons each have 60 hit points, therefore, 80 are killed (4830/60 = 80). One remaining Faerie Dragon unit is reduced to 30 hit points, absorbing the remainer of the damage.
There are various Hit Points Modifiers that can increase or decrease a unit's hit points before a battle. During a battle, Healing and Steal Life can help units recover damage taken during the fight, reviving or creating new units.
