In David Eddings' fictional world of the Belgariad and the Malloreon, there are several means to achieve supernatural feats. There is only one thing that is absolutely forbidden by the nature of the universe itself, and that is unmaking. You can destroy (obliterate, atomize, incinerate), but you cannot undo the creation of something. Uncreation cannot be achieved by any means, not even by the gods or the Necessities.
Demons seem to have supernatural powers, and hence are called upon by wizards to do their bidding. Their power is less than that of the gods, however, as UL bound them to Hell. Their chief aim seems to be to escape this prison. they fear the orb intensely, as is demonstrated in the mountains of Karanda when eriond and garion light the sky up. They all defer to "The king of Hell" a major demon. Some of them are "demon lords' so when summoned, they bring vast hordes of lesser demons.
The are two distinct types. Ulgo diviners have the ability to pass their bodies (and anything they touch) through solid rock. This is helpful in discovering caves, which is useful since they are a subterranean people. Dalasian diviners have the ability to acquire special information.
The power of gods is almost limitless. The gods in the storys are UL (Ulgos), Belar (Alorns), Torak (Angaraks), Aldur (disciples), Issa (Nyissans), Nedra (Tolnedrans), Mara (Marags[extinct, except for Taiba]) and Chaldan (Arends). Oldest is UL, the father god, then his sons Aldur, Nedra, Torak, Issa, and so on to Belar, the youngest.
Very similar to traditional fantasy magic, witches employ potions and spells to achieve certain effects. Magic can be used to prolong the lifespan, but not indefinitely like sorcerers. The only example given is Vordai.
The power of the two Necessities is such that if they were to meet directly, the universe would likely be destroyed. Hence they work through agents, the Child of Light and the Child of Dark, and channel some of their power through the Orb of Aldur and the Sardion to be used by them.
Some Dals have the ability to communicate with spirits of the dead.
Sorcery is the common term for the Will and the Word, which is used by the disciples of Aldur, Torak, and the most senior Grolims. Disciple sorcerers are immune to aging, with other sorcerers living extended lives.
Essentially, a sorcerer borrows energy from everything around him and concentrates it through willpower, then releases it with a word, or phrase symbolic of the action being done. The word itself is not important, but how the completed effect is envisioned by the sorcerer is. (Much of the training and education of sorcerers is toward expanding the power of imagination.) Sorcery requires concentration, and channelling that much power can be physically tiring. One exception is creation: the power for a creative act comes entirely from within. The uses of the Will and the Word are almost limitless.
Sorcerers can "hear" when sorcery is used. This depends on the type of action being done (translocation is very loud), how quickly it is done (you can reduce the "volume" by prolonging the action), and proximity/skill of other Will-talented people. This sense manifests in a way very similar to real hearing, so loud noises can be used to mask the "sound" of using one's Will. Other types of supernatural power are not detectable in this way.
Wizardry is the practice of summoning and controlling demons, practiced primarily by the Morindim and Karands. This is a very dangerous practice, as demons do not like being controlled, and any mistake (such as straying outside the protective circle) gives the demon opportunity to eat the summoning wizard and return to Hell.