Xenology

Xenology, simply put, is the study of magic and its associated schools (abjuration, conjuration, divination, enchantment, evocation, illusion, necromancy, and transmutation) as well as elements (such as fire, cold, lightning, etc.).

Less simply put, it has been theorized the much like there is an astral plane and an ethereal plane, there is also a xenic plane. The precise effects of this aren't entirely understood, but it has been observed that areas which have intensive magic usage will sometimes inhibit the further use of magic. As such, wizards have historically been extremely careful as to where they place wizard towers.