Highly recommendable introduction to the the current requirements for bibliographic metadata. - This chapter of “Understanding the Semantic Web: Bibliographic Data and Metadata” explores the history of library data and where it stands in a modern context. The rise of a new information environment—the World Wide Web—has revealed the downside of the long history that libraries have with metadata. The question that we must face, and that we must face sooner rather than later, is how we can best transform our data so that it can become part of the dominant information environment that is the Web.