Digital library is commonly seen as a type of information retrieval system which stores and accesses digital content remotely via computer networks. A digital library is a special library with a focused collection of digital objects that can include text, visual material, audio material, video material, stored as electronic media formats (as opposed to print, microform, or other media), along with means for organizing, storing, and retrieving the files and media contained in the library collection. Digital libraries can vary immensely in size and scope, and can be maintained by individuals, organizations, or affiliated with established physical library buildings or institutions, or with academic institutions. The digital content may be stored locally, or accessed remotely via computer networks. An electronic library is a type of information retrieval system. Digital Libraries acting as knowledge depositories can be considered as complex information systems, development and use of which require solution of numerous scientific, technological, methodological, economic, legal and other issues. Digital library technologies are rapidly developing. Challenges in semantics, integration of information, and perceptions of presentation of various kinds of data call for significant innovations. Development of Digital library technologies is becoming more and more essential for raising the standards of health care, education, science and economy, as well as the quality of life on the whole. Digital libraries are more and more actively coming into use within scientific organizations and universities. This book, Digital Libraries - Methods and Applications, is an endeavour to share the practical experiences of solutions to the operation of digital libraries. To indicate interdisciplinary routes to successful applications, this book explores the implication of digital libraries from the viewpoints of design, operation, and promotion.