A Potsdam library user can already visit the library online before ever actually setting a foot in the building. For example, the user can find out which library in the neighborhood has the desired book in-stock and if it is currently available for lending out. Other services can be used as well, such as extension of the lending period for media, provision of documents, or reservation of media. Since there is the Kooperativer Bibliotheksverbund Berlin Brandenburg (a co-operative association of libraries in Berlin and Brandenburg), as well as an association of all the public libraries, then it is possible for a desired book or other data media actually located elsewhere to be ordered online from the Potsdam main library.