Types of Magic
External Magic
Runes, sigils, and circles can be drawn and charged by other magic users and left to be activated by non-magic users. While this is most commonly seen in the form of contact-based traps, there are a wide vareity of uses this can have.
Magic tomes, not to be confused with spellbooks, are a third common source. A magic tome differs from a spellbook in that it is often a magic focus, used to channel or store magic. Incantation spells written in the pages can be spoken by whoever holds the tome, using the magic stored in the pages to power it. A spellbook is simply that, a book of spells which doesn't have power on its own. The two CAN be the same thing, if the spellbook HAPPENS to also be a magic tome, which many incantation mages find convenient.
There is another type of external magic, but we will discuss it further down.
Light Magic
Light magic is the collective term for magic that has no "type" so to say. Although there is a concept of dark magic, the two are not actually foils of one another. Non elemental or natural mages usually have light magic. It is very difficult to learn a different magic afinity when you have none, but it isn't a lesser form of magic. Many many general spells use light magic, such as glamours. Magic used by ghosts is also usually light magic, unless they have their body nearby and can draw the affinity they used in life.
Elemental Magic
Elemental factors such as fire, ice, lightning, water, wind, ground, and so on. A lot of elemental mages can only control one element, but can learn to control others with some difficulty. Elemental magic is genetic and the affinity can be passed on to offspring.
Nature Magic
Nature magic is not the same as elemental magic, despite elements being part of nature, although nature mages do have an easier time picking up elements. Nature magic deals with life as a whole. Most nature mages lean towards the control of plant life, but more extreme forms can include controlling not sapient animals and even controlling the weather or seismic activity. This is also a hereditary magic.h some difficulty. Elemental magic is genetic and the affinity can be passed on to offspring.
Fate Magic
Fate magic refers to the sort of magic that influence a person's choices and path, and also to any other magic that can control a person's fate. Many gods use this sort of magic, though it is most commonly known and experienced as the dangerous trickster magic of the fae. Healing magic is also a form of fate magic.
Dark Magic
Dark magic comes in three main forms.
The first is life drain magic. This is the final type of external magic where non-mages can learn to use it. While not inherently malicious, life drain magic sucks the life force out of nearby living things in order to power spells. While this is hardly of consequence for very small spells, only high level mages can control what they're draining life from in order to power their spells, and more powerful spells can wreak havoc on the area around the mage by killing plant and animal life in their immediate surroundings to get enough power.
The second type is necromancy. While technically a sort of fate magic, the matters of messing with the dead have long been considered taboo and evil. It can prolong the life of those on their deathbed, or raise the dead. Unskilled mages might create zombies when trying to create thralls, so rigid learning is required to properly master this sort of magic. While most uses of necromancer magic are considered evil and taboo, there are many benign necromancers. Vampiric magic falls in this category.
The third type of dark magic is demonic magic. Naturally, it originates in demons. Demonic magic has a property of seeping into its surroundings. On a functional level, this could mean spells of other affinities also carry demonic magic. On a larger scale, demonic magic seems into clothes, furniture, and people. Those who passively absorb magic will gain demonic traits the more they absorb, which may or may not be permanent.
Branching from here, there are many different types of demons and therefore, many different types of demonic magic. While all share the above properties, the effects the magic may have varies greatly depending on the type of demon using it. Lust demons, for example, have magic that induces arousal and desire. Imp magic can cause loss of reason and result in madness.
Demons capable of possessing other people or animals will turn that creature into the same type of demon for the duration of their possession, although this varies greatly depending on demon type and, more importantly, the amount of magic the demon has. Weak demons can't do much but whisper in your mind, strong demons can control your body as if it were their own. When leaving a possessed creature, demonic magic is left behind correlating to the length of time spent in the vessel. This magic can be utilized by the host, or it can damage the host. This again depends on the type of demon, and therefore, the properties of magic they possess.
Holy Magic
The antithesis of dark magic is holy magic. Holy magic is used by gods, angels, and blessed others. Like demonic magic, the magic can seep out into other people and objects, and the effects are usually positive as opposed to negative, although high amounts can cause madness to non-mages. Holy magic can be used to directly harm demons physically, but demonic magic can also harm holy users. One is not more inherently powerful than the other, it depends on the strength of the user and the type of creature they are, as angels and gods can vary just as greatly as demons do.
Similar to the way demons can possess, users of holy magic can "bless" others, granting them access to holy magic. Same as demonic magic, holy magic can be left as a residue, stored in a vessel to be used as an energy source, or be contracted to an individual for use. Same as demonic magic, it is hereditary and cannot be learned, only gifted or left behind.