If you're like me, you may have noticed this service on your installation of SharePoint and often wondered what it was.  As a developer, when you see VSS, the first thing you might think of is Visual SourceSafe.  I thought the same, but I knew that couldn't be quite right.  I thought to myself, why on Earth would Microsoft spend time writing integration between SharePoint and SourceSafe.  I decided to look it up.

In this case VSS is not Visual SourceSafe but is in fact the Volume Shadow Copy Service.  Why they didn't call it VSCS, I don't know.  If you are curious as to what the process actually does, it provides integration between SharePoint and the Volume Shadow Copy Service to provide a rich backup experience.  Basically, it describes the data that needs to be backed up to third party backup software vendors.  If you really want to know more, here is the info from Microsoft.  So now you know what it is and this will help prevent you from saying something very noobish such as "SharePoint integrates with Visual SourceSafe out of the box." :)