Following the corruption of Mordagh, Maya did her best to purge this curse from her creation but was unable to completely deny the will of a Greater goddess and so two forms of Magic would be acknowledged on Hyerune.
"Silver Magic" would be defined as magic used as Maya intended. It is magic used to either protect oneself or another but can also be used to combat any force of evil since such an action would help society as a whole in the long run.
"Dark Magic," on the other hand, is magic used purely for selfish or destructive purposes. It is magic that causes harm or creates an effect against the will of Maya.
Both forms of magic are further influenced by the Two Moons of Hyerune. When the Pearl Moon of Celinia is full, saves against the effects of Silver Magic are at -1. When the Pearl Moon is new, saves against the effects of Silver Magic are at +1. Consequently, when the Opal Moon of Mordagh is full, saves against the effects of Dark Magic are at -1. When the Opal Moon is new, saves against the effects of Dark Magic are at +1. These lunar effects only apply at night when the spellcaster is under an open night sky. Being indoors or underground will negate these effects.
A lesser known field of magic is "Gray Magic" which falls under the jurisdiction of Arcanus, the god of spellcraft. Gray Magic is considered "neutral" magic and includes spells that neither directly help or hurt another. Such neutral spells include detect magic and read magic among others.