Magic is a part of the essence of the world. All spell casters utilize magical essence to cast their spells. Scholars disagree as to whether arcane and divine magic are fundamentally different. However, it is clear at least the mechanisms of casting spells and recharging spell abilities are similar, for those casters of the Free Kingdoms.
Magic is readily accepted in the world. It is generally respected, as are its practitioners. Simple folk tend to shy away from users of magic, but such supernatural practitioners permeate all levels of society.
Outside the confines of the Kingdoms, and these odd practitioners are perhaps closer than most scholars fear, there exists a multitude of disparate magics. These types of magics are as varied as the cultures who spawned them. Many volumes in arcane libraries, such as the Great Vault of the Redhurst Academy of Magic, serve as studies of both ancient and exotic methods of spellcasting. From faerie magic to blood magic and even darker practices, the world is full of tales of strange, bizarre, and dark wizardry.
In most civilized cultures of the world, to practice unauthorized magic is considered a sin against the gods and a crime against civilization. To search out and learn such magic is forbidden. Unauthorized possession of tomes on such crafts, or worse, fell grimoires which instruct on the mechanics of such spellcasting, hold severe consequences.
Note that certain organizations, such as The Explorer’s Society, have a limited sanction to discover and secure (and possibly destroy) artifacts and tomes that contain such deviant magical practices. Such adventurers are always at risk, not simply from the terrible nature of their quarry and that which protects it, but from villainous knowledge-seekers who would swoop in and steal those items retrieved at great expense by The Society.