Channels is the legacy mechanism, while Nix Flakes is the modern and more reproducible way of doing Nix things. So, use Flakes instead.
- Installing packages directly from the master branch of Nixpkgs GitHub repository is possible, but risky, since git commits are merged into master before being heavily tested. That’s where channels become useful.
- Read more about channels in this wiki.
- This article is also good for easy understanding.