Windows 10 comes with a built-in backup system called "File History". It allows the user to create a backup copy of files stored on your PC. There are a number of use cases for this feature. For example, it can help you to transfer your files from an old PC to a new one. Or you can use it to backup your files to an external removable drive. It looks like Microsoft is going to remove File History in the upcoming Windows 10 Fall Creators Update.
Windows 10 Fall Creators Update, also known by its code name "Redstone 3", is the next major update to Windows 10. It is in active development as of this writing. Participants of the Windows Insider program regularly receive preview versions of Windows 10 from the Redstone 3 branch.
However, a few days ago Microsoft accidentally released an internal build to Insiders. Users who were able to get Windows 10 build 16212 found new string resources in system DLL files. Microsoft enthusiast WalkingCat spotted the following line:
"Making new backups with File History is no longer supported."
Microsoft might be working on a cloud-based File History replacement which we might see in the future. There is also a possibility that they decided to remove the feature completely based on their telemetry feedback. Anyway, the details are not known yet but features are removed by Microsoft citing low use, no matter how great or useful they are.