Level

Level, simply put, is how powerful you are. The higher your level, the more damage you do with your magic and physical attacks, the less damage you take, the more Vitality you have, and the more spells you can cast before the MP gauge depletes. To level up, you must gain experience. You gain experience by defeating enemies, unless the form or situation you are in requires a different method. Every time you level up, you gain one to three bonuses, which are:
 * 1) Increase in Health Points.
 * 2) Increase in Magic Points.
 * 3) Increase in Strength.
 * 4) Increase in Magic Strength.
 * 5) Increase in Defense.
 * 6) A new ability.

Bonus Level
You do not increase your Bonus Level by gaining experience; rather, you increase it by defeating Bosses. Bonus levels function the same way as regular levels otherwise, gaining the aforementioned bonuses (pre-determined on each fight though), however there's a few more things you can gain:
 * 1) More armor slots.
 * 2) More accessory slots.
 * 3) More slots.
 * 4) A new spell or upgrade to it.
 * 5) An extra Drive Gauge.

Form Level
Every form (except for AntiForm) has a separate level, which experience for is gained by different means than the regular form's "kill enemies" rule, and can only be gained if the conditions are fulfilled while in that form. At levels 3, 5, and 7, you get an upgrade to that Form's Growth ability and to Sora's growth ability corresponding to the same form (at level 3 you gain it, 5 and 7 upgrade it). Forms can have Growth abilities up to Max Level, and regular Sora can only have it up to level 3. You also gain an ability for Sora when the Form levels up to levels 4 and 6, and is in most cases the only way to get them. In every level, you also gain a Form Gauge upgrade.