First of all, we should start out by saying that Google’s support documentation has the best, most in-depth explanation of this if you’ve got the time to really dig deep.
I’m gonna give you a quick, easy-to-understand high-level overview here.
Channels in Google Analytics are there to group data from various acquisition sources in a way that’s useful to you, the marketer looking at your analytics data.
Google gives you a bunch of Channels right out of the box, called Default Channel Groupings.
Here they are:
But you can customize Channels in Google Analytics to better match them for your own needs.