ShadowExplorer allows you to browse the Shadow Copies created by the Windows 7, Vista, 8, and 10 Volume Shadow Copy Service.
It's especially thought for users of the home editions, who don't have access to the shadow copies by default, but it's also useful for other editions.
Windows 7, Vista, 8, and 10 create point-in-time copies of your files from time to time. This allows you to retrieve older versions from files you accidentally deleted or altered. This service is turned on by default on all Windows Vista/7, but Microsoft grants access to these copies only in Ultimate, Business, and Enterprise editions. This is where ShadowExplorer comes into play.
Shadow Copies and ShadowExplorer are in no way a replacement for regular backups! This is very important and can't be stressed enough. A Shadow Copy is kept on the same disc as the original data. In case of a disc failure, all data is lost, including the Shadow Copies. ShadowExplorer is a good addition to regular backups but not a replacement.