Moreover, the principles of topicality and continuity are essential. The information collected by scientific libraries largely consists of works published by the scientific community itself. The information available in libraries is usually protected by copyright. This includes legislation, other government publications, and works on which the copyright has expired. The material is made accessible for the user by describing and categorizing it.
Libraries make catalogues of their collections, and provide the descriptions for subject references.
Making information accessible may also include refining primary information, i.e., adding secondary information to primary information. Making material available Libraries make their collections and connections available to their users. Browsing is also possible in digital files. With regard to lending material and accessing databases that are not in the public domain, the users authorization is always checked by means of access controls. The fact that a public library is concerned with an 'open user group' does not, therefore, imply that there is no control over all the ways of making information available.