A channel is an entity in which you upload your videos. Creating several of them helps you to organize and separate your content.<x id="LINE_BREAK" ctype="lb" equiv-text="<br />"/> For example, you could decide to have a channel to publish your piano concerts, and another channel in which you publish your videos talking about ecology.
The channel name is a unique identifier of your channel on this and all the other instances. It's as unique as an email address, which makes it easy for other people to interact with it.