Magic is the powerful forces that can heal or harm, based on one of two elements. Some people can call powers straight form the mind, with no elements involved, and they are the Psychs, wielding the psychic power of the mind. As stated in the Basics, there are two types of Elements in the world - the Natural Elements [a.k.a. Elemental] and the Crystal Elements [a.k.a. Crystal]. Psychic is neither, being a neutral un-elemented force.
Crystal and Elemental are polar opposites in the grand scheme of things, and a long-standing rivalry over which is better has been ingrained into the world. Both types of elements have two basic raw elements from which all others are derived; for Element it is Rune and Nightfire, and for Crystal, it is Ice Diamond and Black Sapphire. No one in memory is recalled to have ever been able to crontrol those elements or use them other than Kyanth - Guardian of magic and God of the Kanyi. They are simply to unstable for anyone to control properly without risking death, and their nexii almost non-existence in Crystara.
Below are sections more on each, and a link to conversions between element and crystal.
The Rundown on Types
Elemental - The basic building blocks
Crystal - The underestimated powers
Psychic Powers, and their rarity