A Microsoft file hosting and synchronization service.
Even more insidious, is that just after a recent Windows 10 update had installed (June 2025) it showed a full screen notification trying to persuade me to connect my phone to my PC, change my browser to the one nobody wants (Edge, see below) and "set up a backup". It also added a big "Setup a backup" tile in a prime spot on the Start menu, which of course I closed/canceled immediately. What is wrong here is that they refer to OneDrive as simply a backup system, when what they are trying to do is needlessly sync my entire \Documents folder (not that I have ever used their annoyingly stupid default filing system) to OneDrive, charge me when I run out of cloud space, while making me believe I will have made a "safe" second copy of my files. And don't get me started on the Taskbar search icon (which I rarely ever use), to be confronted with a whole bunch of irrelevant Microsoft advertisements. That, and Edge's default home page full of Microsoft's biased selection of "news" and celebrity "entertainment" ©r@p makes me wonder just how stupid the people at Microsoft have become. I am seriously looking at switching to Linux Mint on 14th October, when Microsoft try to hold me to ransom for using their existing product on an old PC, while unhelpfully shoving adverts and half-truths directing me towards their wildly overpriced hardware. Microsoft is going mad in its old age.