There are nine main types of magic practiced in the Continent:
Mage Spells – As is implied, this is magic that is used by trained mages. Often containing a formulaic set of gestures, words, and the like. These have low risk of going wrong, and are rather potent. Very often these spells are elemental in nature drawing on elements like Earth, Fire, Water and Air.
Necromancy (Dark Art) – a subset of normal magic that reanimate, and control. It is highly forbidden type of magic, and practitioners were put to death by the Council of Mages. he revived dead are always unpredictable and reviving them always involves entirely negative side effects. In other words, no matter how noble a mage's motives might be, necromancy will always lead to evil. Thus practicing it is very dangerous.
Source Magic – People who show affinity to use of magic, but are untrained are called Sources, and their magic which is chaotic and unpredictable, and used innately is called Source Magic. This magic is highly unpredictable and may have many unintended side effects. Sources sometime are tapping into the currents of chaos without them intending to, casting magic even when not even trying to. Sometimes they are even possessed by the magic as they do so. These often are associated by heightened emotional states. Sources can sometimes cast magic far beyond the ability of others better trained individuals, and cast spells that are strange or unknown. But they tend to eventually lose connection to reality, go mad, or destroy themselves utterly.
Druidic Invocations – Druids do not tap into Chaos themselves. Instead they use their connection and understanding of nature and its spirits, invoking their powers into elemantal magic. Chaos is still what powers the invocations, to be sure, but their source seems quite stable. Those tend to coincide with things like plant manipulation, animal control, some basic elemental spells etc.
Priestly Invocations – Priests invoke their respective deities to channel magic through them. Many a mage already determined that most deities use Chaos somehow. But gods don't often share their secrets. It is surmised that the deity is being powered by the emotions of their followers and can thus bestow some of that power onto the priests through the chaos link of emotion and conviction.
Rituals – These spells can technically be performed by just about anyone. Magical potential seems not to have much bearing on it. But rituals are quite complex and hard to perform, and require a lot of foreknowledge and skill, and thus are available to very few. Even some accomplished mages often know only two or three rituals.
It is often theorized that the Lay Lines (magical vectors that run along the ground, akin to brooks or rivers) are what power ritual magic, thus performing rituals over Lay Lines, and especially over crossings or places of power is advised.
Curses – Curses are quite a mystery. They seem not to be powered by chaos at all and instead manifest themselves as powers of fate itself. Curses are very potent. Those bestowed by utterance are usually made by a person of some significant magical ability at their emotional extreme, uttering words that shape fate itself. These are very hard to break or lift, or even resolve, and only few accomplished Mages and Witchers managed this feat. These usually are also quite dangerous to those who would try to lift them as curses are able to manifest specters and other unnatural monsters.
Curses sometimes don't even need a bestowing, as creation of some Cursed Ones like Botchlings proves. It is surmised that some curses appear of grievances of fate and proper conduct.
Hexes – A lesser type of curses that has a formulaic way to bestow them, and often possible to lift with an equally formulaic way. Thus these are better understood than curses, though they seem to be very similar from the nature of the power that feeds them. However, it doesn't mean that Hexes are a mere nuisance. To the people afflicted by them, they can be quite dangerous.
Goetia or Demonmancy (Dark Art) – dealing with demonic entities from beyond this world. Entities that are often quite evil. Little is known of Goetia, and for good reason.