The Volume Shadow Copy Service is a technology included in Microsoft's systems that allows the execution of file and volume consistent snapshots. Thanks to the VSS service, it is possible to back up the files or volumes, even when they are being used, so to say, while you are working on them.
By default, the application uses the VSS service when performing a backup, but the user has the ability to disable this option
One of the most important arguments for using VSS is to maintain data consistency. If there are any dependent files on a disk, thanks to the snapshot, you would be able to restore them from exactly the same point in time. It is worth noting that Xopero ONE creates a snapshot on all disks included into the copy simultaneously