There are four elements: fire, air, Tibia and sula.
Long time ago, there was no elements, only Tibiasula. She was the perfect unity of the elements. When Zathroth killed Tibiasula, all elements were jerked out.
As Lynda and Tibra say, the Elements are the gods of good.
Pydar says: The ways of the gods are imprehensible to mortals. On the other hand, the elements are raw forces and can be understood and tamed. Important thing - the elements can be understood and controlled.
Many information about elements: fire and earth can be found in Kazordoon. Geomancers are followers of earth and Pyromancers are followers of fire.