This will probably be the shortest post in this series.
A key question for any fantasy world, regardless of sub-genre, is who can learn or perform magic?
There are myriad approaches to answering the question, many of which mix a couple answers simultaneously. But, I think the answers can be boiled down to three possibilities:
1) Magic use is genetic among the world’s primary species (usually humans).
Mages are those who inherit the talent from their parents. Their parents may or may not be mages themselves, as with all genetics it is possible for latent traits to skip a generation or two. This is the wizard/witch magic of Harry Potter, Eragon, and a lot of current urban fantasy. Study is usually required, to control the talent, but without the talent the magic doesn’t work.
2) Anyone can learn magic if they simply study hard enough or are initiated properly.
Magic is simply a matter of being initiated into the right mysteries or studying the right subject(s) in school. Anyone can potentially become a mage. This is a more historical magic, particularly according to 15th to 18th century European and American writings on witchcraft—there involving a pact with a devil—or records regarding astrology, alchemy, and related magics in the same era—most of the magicians were educated men who learned “occult arts” while they were learning philosophy, medicine, and law. The important part is that no special, genetic, talent is needed to learn.
3) Every species has its own kind of magic.
A more involved worldbuild, but one that has significant use in the genre, is one in which every species possesses its own variety of magic. In these cases, magic may still be learnable or innate depending on the species. Middle Earth is a great example, in which the elves had their own magic, the Istari had their own, and other species had theirs. Likewise, Michael Moorcock’s Melniboné can be included as different species have access to different magics—Melnibonéans versus humans—due to ancient pacts with Law, Chaos, and elemental beings. Or White Wolf’s World of Darkness line—mage magic is different from shapeshifter magic is different from fae magic is different from vampiric magic.
Based on a long time reading in the genre, those are the three broad approaches that come to mind as I consider this topic. Whether there are others, well, I’m sure there might be and I’d be happy to hear about them because as much as I’ve read in the genre, there’s probably 10x as much that I haven’t been able to get to.