There are eight Elemental Planes, though only the most prestigious Casters can access the Light and Shadow realms. The other six are accessible by most Casters and are in general, a lot more is known about them. Each Elemental Plane is home to Elementals of its respective type, as well as Genies of its respective kind and sometimes other Elemental Creatures.
Efreeti/Efreet
Qorrashi/Qorrash
Khayal
Dao
Marid
Djinni/Djinn