These represent the feature update cycles for Windows 10.
If you are looking to download or learn about , Key Features of Lite Builds Download Windows Lite Version 21H2 21H1 Build 1904X 1387 zip
Because these are created by third parties, they do not come from Microsoft. There is a risk that the ISO could contain malware or that essential security patches have been disabled [4]. These represent the feature update cycles for Windows 10
[4] Cybersecurity advisories regarding unofficial OS distributions Download Windows Lite Version 21H2 21H1 Build 1904X 1387 zip
You still need a valid Windows license key to use these versions legally. How to Proceed