An Element is one of the four basic building blocks of magic. It forms some of the schools and colors of magic. The elements include fire, earth, water and air. Perhaps aether or essence makes up a fifth element that binds all the rest together.
While there are schools of magic devoted specifically to each element. There are other schools devoted to the 'black' or 'white' magic as well (it is unclear if the magics of 'Darkness', 'Chaos,' 'Life' and 'Death' are associated with the elements as well).
When an element takes on a sentient physical manifestation it is known as a elemental.