This book is the first to provide an integrated overview of the field, including the concept of digital libraries, transition of libraries from traditional to digital, design and organization of digital libraries, their architecture, interoperability, protocols and standards. The term “digital libraries” covers the creation and distribution of all types of information over networks, ranging from converted historical materials to kinds of information that have no analogues in the physical world. In some ways digital libraries and traditional libraries are very different, yet in other ways they are remarkably similar. People still create information that has to be organized, stored, and distributed, and they still need to find and use information that others have created. An underlying theme of this book is that no aspect of digital libraries can be understood in isolation or without attention to the needs of the people who create and use information. Although the book covers a wide range of organization and management, files & formats, the focus is on the actual working components of a digital library which is open source software for digital libraries: GSDL - DSpace – EPrints. The technological interoperability of digital libraries must be rethought in order to adapt to new uses and networks. Informative digital environments aimed at responding to heritage, cultural, scientific or commercial demands have taken over the global cyberspace and have redesigned the techno-informative landscape of the Web. However, while the technological models demonstrate their effectiveness and explain to a large extent the creation of digital libraries, archives and deposits, the subjacent concept of uses continues to cause debate. The information technologies used by heterogeneous digital libraries enable a technical interoperability of content. This is not enough to allow the adhesion of a public connected to very different information profiles and techniques. This book explores the avenues of a user orientated interoperability where the questions of consultation interfaces and content description processes are studied.