Ragnarok Online/Controls

Attacking
When you attack, be aware of your HP and SP bar.

HP and SP
Your characters HP will decrease if a monsters attack connects. You can regenerate your characters HP or SP with usable items or through natural regneration. Both HP and SP regenerate on their own when the character is not moving, and at twice the speed if the character is sitting down. If the character holds more than 50% of their total weight limit, they cannot naturally regain HP or SP. If your HP bar reaches 0, your character dies and will be returned to their set save point.