"Transfiguration is some of the most complex and dangerous magic you will learn at Hogwarts. Anyone messing around in my class will leave and not come back. You have been warned."
     -- Minerva McGonagall

Transfiguration is magic which changes one object into another. It is possible to change inanimate objects into animate ones and vice versa. Some Transfiguration spells alter a part of something, such as changing a person's ears from normal into rabbit ears. At Hogwarts, Transfiguration is taught by Professor McGonagall. Fifty years ago, Dumbledore was the Transfiguration teacher at Hogwarts (CS). Transfiguration spells were cast in ancient times as well. Circe, a Witch who lived in the Greek island of Aeaea, was famous for turning lost sailors into pigs (CS/g).

transfigurations
Hagrid tries to change Dudley into a pig (SS4)
McGonagall changes her desk into a pig (SS
students try to change match into a needle (SS
Switching Spells (SS9)
student accidentally changes his friend into a badger in class (CS
cross-species switches (GF22)
change guinea fowl into guinea pig (GF
change porcupine into pincushion (GF
change buttons into beetles (
Cedric transfigures a rock into a dog to distract the dragon (GF
learn human transfiguration in the sixth year at Hogwarts (GF26)

books about transfiguration
A Beginner's Guide to Transfiguration by Emeric Switch
Intermediate Transfiguration
Guide to Advanced Transfiguration
Theories of Transubstantial Transfiguration