About
A channel has a name or identifier (e.g., user_signed_up) that supports a single type of message.
Channel may also be referred as:
- topics,
- routing keys,
- etc.
All brokers support communication through multiple channels.
Analogy
Channel is a concept borrowed from TV or radio channels where they broadcast their information through an assigned channel.
If the broadcasters (publishers) didn't publish its channel, you (the subscriber) wouldn't be able to tune in.