Files with the .VBK extension contain DRM-protected digital boosk published by one of the many publishers in the VitalSource Bookshelf application.

The VitalSource Bookshelf application is used to support and read purchased eBooks. In order to read VBK files, the user must have an account in the system and an application – called the client. VitalSource Bookshelf also provides access to digital versions of some books purchased in paper form.