The traditional face-to-face reference desk existed in an environment where information resources were physically concentrated. The reference librarian in many ways operating as a gatekeeper was well-versed on the content, location, and accessibility of these resources, and a familiarity and working knowledge of sources was considered fundamental to the field. Because most of the sources reference librarians are using today are digitally based, the sources for virtual and face-to-face reference tend to be the same, and they cover a wider range of formats and types than ever before