The range of metadata needed to run a digital library and preserve its collections in the long term is much more extensive and complicated than anything in its traditional counterpart. It includes the same 'descriptive' information which guides users to the resources they require but must supplement this with comprehensive 'administrative' metadata: this encompasses technical details of the files that make up its collections, the documentation of complex intellectual property rights and the extensive set needed to support its preservation in the long-term. To accommodate all of this requires the use of multiple metadata standards, all of which have to be brought together into a single integrated whole. Metadata in the Digital Library is a complete guide to building a digital library metadata strategy from scratch, using established metadata standards bound together by the markup language XML. The book introduces the reader to the theory of metadata and shows how it can be applied in practice. It lays out the basic principles that should underlie any metadata strategy, including its relation to such fundamentals as the digital curation lifecycle, and demonstrates how they should be put into effect. It introduces the XML language and the key standards for each type of metadata, including Dublin Core and MODS for descriptive metadata and PREMIS for its administrative and preservation counterpart. Finally, the book shows how these can all be integrated using the packaging standard METS. Two case studies from the Warburg Institute in London show how the strategy can be implemented in a working environment. The strategy laid out in this book will ensure that a digital library's metadata will support all of its operations, be fully interoperable with others and enable its long-term preservation. It assumes no prior knowledge of metadata, XML or any of the standards that it covers. It provides both an introduction to best practices in digital library metadata and a manual for their practical implementation.