The Hitpoints skill determines the maximum amount of Hitpoints you can have. Hitpoint experience can be earned by dealing damage in the combat section. 1.33 XP is awarded per point of damage done to enemies.
Hitpoints are passively regenerated at a rate of 1 per second. This rate can be increased by equipping a Gold Ruby Ring, which changes the rate to 1-3 per second or the Hitpoints Skillcape which increased the rate by 5 per second. Hitpoints may also be regenerated by eating Food.