Channels are nodes that can contain other nodes. Channels include: forums, blogs, social groups, private messages, visitor messages, user albums, and flagged (reported) content. Some channels can be maintained with the Channel Management (formerly Forum Management) tools in the Admin CP. Others are private (hidden from view) and maintained by individual users.
A channel owner is the user that has ownership of a particular channel. Owners control what happens in the channel. Blogs and social groups are examples of channels that can have owners.
A channel moderator is a user appointed by the channel owner to moderate a particular channel. Blogs and social groups are examples of channels that can have moderators.
A channel user is an individual who has permission to access a specific channel. A social group is an example of a channel that has users.