A channel points to a specific deploy build of your app that will be shared with any devices configured to listen to that channel for updates. You can change the build a channel points to whenever you'd like, and can rollback changes as well.
Every app comes with two default channels: Master, and Production.
Common use cases are using a Production Channel for your App Store binaries, and the Master channel to run a native binary on your phone during development that gets automatically updated.
Once you've set up a Channel, just click Set Up Deploy next to that Channel and it will walk you through the options available and generate the Command Line command that you should run.
To create new channels beyond these two, you must have a paid Ionic Appflow membership. To add new channels, simply view the channels list by going to Deploy -> Channels, and then click the New Channel button.
Once you have created a Channel, go back to the Builds section of your app. On the right side of each Build, you'll see a "Assign to Channel" icon.
Click this to set the Build as active for a Channel.
Once a Build is set as active for a Channel any native binaries that have been set up with Ionic Deploy for this Channel will receive the new update next time they check in.