Classes at Hogwarts

Arithmancy - ancient study of the magical properties of numbers.

Defense Against the Dark Arts - Magic lessons at Hogwarts that teaches students how to defend themselves against evil creatures. The teachers were, Professor Quirrell, Professor Lockhart, Professor Lupin, Professor Moody, Professor Umbridge and Professor Snape.

Divination - Magical art of telling the future. Taught by Professor Trelawney

Herbology - Study of plants. Taught by Professor Sprout. This is the only class Neville Longbottom is good at.

Muggle Studies - Class taken by wizarding folk to study non-magical people. 

Occlumency - A special class that teaches magical defense of the mind against external penetration; seals the mind against magical intrusion and influence. Only someone skilled at Occlumency is able to shut down those feelings and memories that contradict the lie, hence is able to utterfalsehoods without detection. Dumbledore urges Harry to study this to protect himself from Voldemort. An obscure but highly useful type of magic; taught by Snape.

Transfiguration - The art of turning one thing into another. Taught by Professor McGonagall.