Magic was a practice, usually considered evil, practiced by witches and various other people.
The most common magic, especially in the Dark Ages, was necromancy. This is dark magic, including summoning the dead.
Witches would often make potions. These potions could be made from body parts of animals, or enchanted objects.
Wickens would not actually practice magic. They would make potions from herbs and plants, usually healing potions. Many people thought they were evil, so they would kill them.
Apprentices are the lowest class in magic. They are just beginning training.
Mages are the most common class, and fairly powerful.
Socerors and Sorceresses are high class, said to use many types of magic. They are usually depicted in cloaks.
Wizard is the highest class. They are usually depicted as wearing robes and a cone-shaped hat.