The preservation of digital information over long periods of time represents one of the central challenges in the digital age. While analog media such as books or microfilms remain readable for centuries when stored appropriately, digital information is subject to rapid technological change—both in terms of storage formats and the required hardware and software. Therefore, this chapter first addresses the topic of digital long-term archiving in Subsection 4.1, with a particular focus on the role and structure of metadata, as these serve as the foundation for the long-term availability, discoverability, and usability of digital resources.