Shadow Copy (also called Volume Snapshot Service or VSS) is a feature in recent versions of http://www.answers.com/topic/microsoft-windows that allows taking manual or automatic backup copies or http://www.answers.com/topic/snapshot-game of a file or folder on a specific http://www.answers.com/topic/volume-computing at a specific point in time. It is used by http://www.answers.com/topic/ntbackup and the Volume Shadow Copy service to backup files. In http://www.answers.com/topic/windows-vista, it is used by Windows Vista's backup utility, http://www.answers.com/topic/system-restore-1 and the Previous Versions feature