Reference service, the idea that librarians provide direct assistance to users, has been a central function of libraries for over a century. Today's libraries are even more complex and intimidating to new users than libraries of the past, and the technical and social contexts in which users experience their library's resources add to this complexity. The availability of a friendly librarian who helps users find materials, search for information on a topic, interpret citations, identify quality information, and format bibliographies has become a standard component of what libraries do....