There are four main types of channeling that fall along a wide spectrum. All of these states, except for the first, involve an altered state of consciousness to some degree:
Full-conscious channeling
Altered-state conscious channeling
Light-trance channeling
Full-trance channeling
Someone who is a full-conscious channeler remains in his (or her) usual state of normal consciousness: He can move around, stop, and then restart the process. Altered-state conscious channeling occurs when the channeler feels fully conscious, but later realizes his focus was somewhat different from his normal thought processes. Trance channeling involves someone who seems to enter another realm. A light trance is less intense, perhaps occurring telepathically between the spirit and channeler's minds. A heavy trance involves the channeler's complete loss of consciousness, perhaps occurring when a spirit enters the person's body.
Although the historic stereotype portrays the channeler in a full trance, a new school of channelers (or at least a new group of those who are willing to talk about their experiences) is inclined to be more conscious while channeling. No one way is best for everyone. Each person's comfort level and increased spiritual insight are what matter most.