Chromebooks are built on top of Linux, but it wasn't until 2018 that Google integrated the Linux desktop into Chrome OS. Then years went by with Linux only available as a beta on Chromebooks. But, at long, long last with the release of Chrome OS 91, Linux finally become a first-class citizen on Chromebooks.
MInd you, long before Google integrated Linux into Chromebooks, you could run desktop Linux distros on Chromebooks. With the open-source Crouton program and its chroot container, you could run Debian, Ubuntu, and Kali Linux. Or, you could run Gallium OS, a third-party, Xubuntu Chromebook-specific Linux distribution.
Or, you could do what I've been doing for the last three years, just running Debian Linux using Google's Crostini. This KVM virtual machine (VM) system with its LXD Linux containers may have been a beta but I never -- I repeat -- never had any trouble running Linux with it on all the many Intel-based Chromebooks I've used in the last few years.
But, now that Linux is officially supported, you can run multiple Linux instances at once on your Chromebook. This will be a big deal. Do you want to compile your code in one container while playing Tux Racer in another? You can do that.
Well, sort of. In practice, even on my maxed Pixelbook Go with its i7 processor and 16GBs of RAM, both containers stutter a bit. You see this feature is still a beta with a capital B.
To make it work, you need to enable the new 'crotini-multi-container' flag. There's also a new Chrome OS Settings section, "Manage extra containers". This both tells you what your current containers are, lets you create a new one, and enables you to stop or delete your existing containers. In my early testing, I've been stopping a lot of misbehaving containers.
In short, this new feature is far from ready for ordinary use. But, if you like playing on the bleeding edge of technology, it's well worth a try. Eventually, when this new functionality is perfected, this will make high-end Chromebooks as useful for Linux power users as a top-of-the-line Linux laptop like a Dell XPS 13 Linux Developer Edition .