Channeling is the ability of a psychic or sensetive to hear, see or sense a spirit, and then relay messenges from the spirit.  The spirit can be guides, relatives who have crossed over, or angelic beings.  Channeling is much the same as mediumship.  Mediums and Channels can be considered messengers.

One type of channeling is called a trance channel, and they allow a spirit or entity to take control of thier body and voice. The voice of the channel many times will change, and most "trance channels" do not know what was said after the channeling session.