Experience Points (or EP) are useable Adventure Points. Experience Points are used to increase character values, attributes, talents, spells, or to learn new abilities. You earn 1 Experience Point for each Adventure Point earned. In other words, every time a character receives an Adventure Point, he also receives an Experience Point, which he can spend as he pleases.
With Experience Points the Attributes, Talents, Spells, as well as Vitality and Astral Energy of a character can be raised. The higher their current values are, the more expensive it becomes to raise them further.