Acrobatics is the skill where you level up from taking fall damage, successfully dodging an attack from a mob/player, and successful rolling or doing a graceful roll. Note: Teleporting anywhere within 5 seconds of taking fall damage will not grant xp.
Perks of leveling up Acrobatics:
Graceful roll: Is an active ability that works whenever you are crouched while falling this ability can negate up to 7 hearts of fall damage. Graceful roll chance is gained at 0.2% per level of acrobatics. This ability caps at 100% at 500 Acrobatics.
Roll: Is a passive ability that automatically is applied whenever you fall. The skill can negate up to 3.5 hearts of fall damage. Roll Chance is gained at 0.1% per level of acrobatics. This ability caps at 100% at 1000 Acrobatics.
Dodge: This is another passive ability that halves all combat damage taken. This ability gains 0.025% per level of acrobatics up to a cap of 20%at 800 Acrobatic levels.