The third edition of this book will reach across disciplines and address the needs of not only those who study, evaluate, and purchase health information, but also computer and library/information scientists, information technology developers building databases, search engines, Web sites, and other systems for universities and hospitals who enthusiastically read the first two editions. The book is divided into three sections: Basic Concepts, State-of-the-Art and Research Directories. Major changes to the this edition will include a new chapter in the State-of-the-Art section on Digital Libraries and a new focus on areas related to information retrieval systems covering such topics as electronic publishing of journals and other scientific materials, emerging standards, open access publishing issues, digital preservation, that summarize and categorize documents to handle the vast amount of information that is now available. Web updates, which include keeping track of new systems, technologies, studies, are folded into the third edition to show the advancement from 1996 to present time.