A Microsoft file hosting and synchronization service.
This is complete garbage, Microsoft.
I have a paid OneDrive service through a Microsoft 365 Family subscription. We're supposed to get 1TB each for 5 people and I had shared folders set up between two of my Microsoft accounts (two laptops) and my wife's account (her laptop). We had shared folders that we could transfer photos and such between us, just by looking in the shared folders in File Explorer and cut/pasting files that would sync between the machines. Then, like many, I noticed today that a few weeks ago (?) it suddenly converted these shared sync folders with files to web links that just open the OneDrive web view to access the shared folders and files remotely (and VERY inconveniently).
While that was SUPER ANNOYING and not what I paid for, whatever change they made also DELETED the previously syncronised shared files and folders on my C drive in the OneDrive file tree under c:\users[username]\OneDrive path, replacing the folders with web link shortcuts. This is Microsoft DELETING data on MY local disk WITHOUT MY PERMISSION. Absolutely outragious.
I don't care what Microsoft says about whether it wants to continue to provide folder sync services as part of the service I PAID for, deleting MY data without MY PERMISSION on MY disk has to be illegal.