Students who major in demonology will naturally learn about demons. They will learn about the various beliefs about demons, as well as the history and nature of the creatures as well. Remember, not every demon is evil... they just may have negative thoughts about you.
First year students will embark on a journey to understand the various forms of demons in many different cultures of our world. How to safely enter contracts with said demons, or how to properly employ their services are other parts of this study. First years are warned not to overextend themselves -- demonology is indeed one of the more dangerous subjects to study at the school!
Summoning one's personal familiar is usually one of the first things a first year will be taught to do.
The magic to invoke demons and create contracts is of a very ritualistic nature.