All your multiple PCs have the same Documents folder. Files created on one PC are synced to the cloud and appear in all the other PCs' Documents folders, and will be downloaded to the local storage if you try to access them. You get a small icon next to each file or folder to try and tell you if the files are local or in the cloud or whatever status. If apps are saving data to synced folders (eg. all those many many games happily polluting my Documents folder), then that same data is available to the same app on different computers. Could be good, or bad if the apps are being used on different computers at the same time with no real way of determining which PCs changes win for which particular file.