If you want to beta-test Windows versions before everyone gets them, the Insider Program currently has a few release channels ranging from relatively stable to extremely buggy. A new canary branch, though, is taking over as the most bleeding-edge channel.
Microsoft has announced a new Canary release channel for the Insider Program, which will let people try out fresh, just-cooked additions to the Windows operating system. Here, Microsoft will release "hot off the presses" builds of Windows to Insiders --- presumably, that means they will go straight from internal "dogfood" testing to canary testing with little to no validation or documentation.
These new canary builds will start out with 25000-series builds of Windows 11, and they might also be the place where we first see publicly-available builds of Windows 12 whenever they do become available. After all, there have been strong hints and rumors of a new major version of Microsoft's operating system in the near future.
Microsoft also said it will be using this channel for testing the kind of platform changes that need more thorough testing before shipping to users --- a new major version would fit that description. The language in Microsoft's press release seems to avoid tying Windows 11 to this new canary channel. We're just speculating here, but anything could happen.
This doesn't mean we'll see Microsoft release Windows 12 anytime soon. In fact, the first few Canary builds will probably be Windows 11. But even if we do, you shouldn't install this on your main PC. These will be unstable builds with little documentation, and stuff might break.
People currently in the Dev channel will be upgraded to Canary starting today. The Dev channel will continue to exist, but it's being repurposed to provide better platform stability than Canary. But if you want to continue getting Dev builds, you'll need to do a clean install of Windows.
Source: Microsoft