Live11 is an optimized version of Windows 11 designed to fit on a 4GB drive and run entirely on RAM - which means it's the first version of the OS that can fit on a DVD. Not that you'd still have access to something like a DVD burner, Live11 can also be stored on a smaller-capacity USB thumb drive.
Live11 is still in the proof of concept stage, so there are issues. It will only boot on legacy MBR/BIOS devices and requires 8GB of RAM to load. Plus, it's limited to VMware and Hyper-V for those looking at running it on a virtual machine. Still, it's remarkable that you could try our Windows 11 on a PC without installing it on a hard drive or doing a complete format.
Of course, the concept of a Live disk is more common in the Linux space than in Windows, so this release is notable for what it achieves.
Live11 comes from developer NTDEV, the creators behind Tiny11, a lightweight Windows 11 that can run on older lower-end PCs. It's based on Windows 11 Pro 22H2 and offers the full Windows 11 experience without all the bloat and clutter of a standard Windows installation. Tin11 was already a remarkable feat in that it only takes up 6.34GB, so Live11 pushing this to 4GB and running on RAM is impressive.
Still, without the ability to install apps and write to disk, it's a read-only experience with limited apps and storage mainly used for temporary files. The ISO contains a portable version of Firefox (Live11 doesn't have Microsoft's Edge browser), so you can browse the web - which is a must for any modern OS.
If you want to take Live11 for a spin, you can grab the ISO image from the Internet Archive. Fair warning, this isn't an officially supported version of Windows, so there's no official support available.