In this book Kaj Gronbaek and Randall H. Trigg present a set of principles for the design of open hypermedia systems and provide concrete implications of these principles for issues ranging from data structures to architectures and system integration, and for settings as diverse as the World Wide Web and the workplace.The principles, which cover both hypermedia system processing and data structures, reflect results from decades of hypermedia research, including the popular Dexter hypertext reference model and the authors own extended object-oriented version of the Dexter model. One important principle is the notion of links as first-class objects outside the data. Emerging systems such as HyperWave, Microcosm, and Devise Hypermedia apply this principle to extend the capabilities of the Web. The authors also discuss the management of incomplete and dangling links, time-based media including video and sound, support for collaboration and shared hypermedia structures, worldwide distribution, and integration of third-party applications in open hypermedia systems.