HP, which can stand for Health Points or Hit Points, is an important stat in every game of the Final Cross series. Every playable character, monster, and Summons in some games, have a set HP. Once all HP is depleted, the character falls into the Knocked Out status and must be revived, for example, by using a Fenix Down. Revived characters are always given some HP back.
Only characters in the Zombie status can have 0 HP. They are immune to most attacks, and must be healed with Holy Water. Most offensive attacks target HP. Monsters usually disappear from the battlefield when their HP reach zero.
There are many abilities that restore HP, but it is mostly typically healed by the spell Cure or the item Tonic, or a stronger version of either one. The spell Regen slowly restores HP. The spell Poison slowly depletes HP. Drain sucks away HP from the target and gives it to the caster. Death, if successful, instantly removes all HP. Undead monsters have reverse effects upon their HP and are immune to or healed by Death.
Other than the normal status and the Knocked Out status, there are other additional statuses tied with HP. A character with a low HP in relevance to their Max HP will fall into the HP Critical status where their pose will change and HP will become yellow or red. In this status a number of other occurrences may happen, such as an ally protecting them with Cover or gaining access to Overdrive abilities. Enemies in Critical status usually won't change pose, however susceptibility to certain abilities will be introduced such as the Morph ability.
In Final Cross the amount of HP that characters gain on a level up correspond to the job skill they were in at the time they leveled up the party is fully healed whenever they touch a Save Point.