Magic is the controlling and channeling of Aether, often through a medium such as a Staff or Rod, to perform various spells and incantations. There are several schools of magic, such as Black Magic, the control of the Elements to perform powerfully destructive spells, or White Magic, the channeling of aether to soothe and heal, or remove various maladies. There are also mixes of these schools of magic, such as that used by the Red Mage to bring both schools together, or the school of magic used by Arcanists, scholars and Summoners to breathe life into magically-receptive gems and jewels to call forth familiars.
Almost all living beings are able to channel aether in such a manner, such as a Raptor using their own aether to breathe fire or other creatures using the ambient aether around them to rend the earth. The more proficient a being is in channeling the aether both within and around them, the more powerful their spells are.
A more controversial use of magic is the summoning of Primals used by the Beast Tribes of Eorzea, which, while similar to the method employed by Summoners to call forth their Egis, is much more taxing on the land and produces far more dangerous results. This form of summoning is based on fervent prayer, and is channeled through massive quantities of Crystal to bring forth the gods of their particular belief systems. More often than not, these "gods" are fanatical shades of what the tribes worship, often affected by the vengeance or malice of those summoning them and hungry for more and more aether. A side effect of these beings being summoned under duress is the Beast Tribe's desire to conquer their foes manifesting in the Primals as the ability to Temper their victims, tainting their aether and turning them into mindless thralls. This effect lasts even after the Primal is slain, and until recently was believed to be incurable.