National libraries hold large, valuable repositories of often unique materials. How can we ensure that the knowledge is accessible without endangering the materials that hold the knowledge? Digital preservation is meant to solve this problem. With more and more material being accessible digitally, users are expected to do more and more of the finding on their own, instead of being guided by librarians. What kind of knowledge do the librarians have, that cannot be mediated through a system? How is the knowledge of experienced librarians passed on to new librarians? What is the difference between physical and digital materials? I have interviewed senior and junior librarians of Det Kongelige Bibliotek in Copenhagen, Nasjonalbiblioteket in Oslo, the National Library in Helsinki, and Kungliga Biblioteket in Stockholm to learn about their journey to knowledge of their collections.

The National Libraries task to save and preserve the national cultural heritage has turned to a new challenge in a digital world. The preservation of born-digital material for future use requires not only saving the digital object itself but also information about the object, preservation metadata. This is a relatively new issue and the library community has very little experience in this area. It has become evident that international cooperation is necessary to solve the task and that the development of international standards is of fundamental significance. This thesis investigates what has been done to meet the problems with the fast obsolescence of digital material with the focus on metadata.

The departure point of this thesis is the context of the institution and the processes surrounding the handling of personal archives at the National Library of Sweden. These processes are examined using Actor Network Theory. Around the personal archive a network is constructed and contained by actors ? the archive itself, the librarian, the conservator, the researcher, organizational structures and others. Within this network choices are made of what is significant.

Close to the city center of Reykjavik lies the combined national- and university library of Iceland. Usually, these two types of institutions are separated. The purpose of this essay is to investigate how the library in fact selects the new digital material to offer the users in Iceland, and if the combined mission creates any problems or conflicts.The investigation examines the planning and the content of the digital library, what user groups are addressed and how the organisation is held together despite the different missions. If cultural context in Iceland makes a difference for what is selected and offered to the users is also discussed.Six informants in strategic library positions dealing with the digital national- or university library, were interviewed. The answers have been analysed in light of the library&information literature on building and maintaining digital library collections and organizational and marketing theory.The main result of the study is that the informants do not see a conflict between the missions of the organisation, although traces of a struggle were found in some areas.