Elemental Magic is a group of magic schools which allow magic-users to manipulate the four elements (fire, water, air, earth). It can be done both by manipulating the elements around the caster and by generating the element. Though it is possible to master all four most magic-users decide to specialize in only one of them, because of the complexity of a single element. Elementalists, masters of all 4 of them, are very rare.
Energy from the outside
Elemental mages can enhance their power by the energy of elements around them. Aeromancers and Geomancers can do that almost always as these elements are omnipresent. Pyromancers and Hydromancers have more difficulties with that, but it doesn't mean that they can't enhance their power. Hydromancers can force the water out from plants or animals in order to use its energy. For Pyromancers it is a little bit more complex. It said that a person's capability for anger is dormant fire. Skilled pyromancers can use it to enhance their power.
There is a hypothetical 5th element which is not related to the natural world in the same way as the the basic four elements. There is a big and heated debate about what is the 5th element. Some people say that spirits are it. Others say that it is magic. Supporters of the spirit theory claim that one of the few magic-users utilizing the 5th element were Holy Warriors of the Guanches, a group from the Canary Islands.