From Kook Science
Mediumship (or channelling) is the art and practice of the medium, an individual who acts as the host body, willingly or not, through which a force, such as a spirit or outside intelligence, acts to produce an effect. The three general classes of mediumship are trance mediumship, mental mediumship, and physical mediumship.
Trance mediumship is a form of mediumship that involves the medium entering into a trance state, becoming a passive receiver through which an outside control is enabled to write, speak, or otherwise transmit an effect. This is distinguished from mental mediumship, where the medium is aware of the activity.
Mental mediumship involves the medium retaining full awareness and utilising their own psychical abilities, including clairvoyance or clairaudience, to engage with an outside force, such as a spirit or psychic communicator.
Physical mediumship involves the medium acting as a conduit for physical manifestations of psychic phenomena, as is seen in demonstrations of the spirit trumpet voice, ghost lights, levitation, apportation and materialization of objects, among others.