Wizards are, as usual, massive nerds. The fabric upon which all mortal magic is cast is called the Weave, and it was created/woven by Auro, God of the Weave way back when. Its theorized that it is sapient and yada yada, read more in Auro's profile.

The point is, Wizards are people who scientifically picked apart how to manipulate the weave without any necessary innate magic. Wizards are trained to be quite in-tune with the weave, even to the point of detecting strong magic and spells cast nearby.

Most wizards are trained in universities or academies, of which there are quite a few across the world (many also are temples to Oculon, Deity of Knowledge or Auro, God of the Weave). There are also wizards who are self-taught, or have an innate talent in picking out these patterns.   Wizards dont necessarily worship Auro, God of the Weave, although there is a subset that believes its the best way to become better.