As the Web continues to grow, increasing amounts of data are being made available for human and machine consumption. This emerging Semantic Web is rapidly entering the mainstream and, as a result, a variety of new solutions for searching, aggregating and the intelligent delivery of information are being produced,bothinresearchandcommercialsettings.Severalnewchallengesarise from this context, both from a technical and human-computer interaction p- spective - e.g., as issues to do with the scalability andusability of Semantic Web solutions become particularly important. The International Semantic Web Conference (ISWC) is the major inter- tional forum where the latest research results and technical innovations on all aspects of the Semantic Web are presented. ISWC brings together researchers, practitioners, and users from the areas of arti?cial intelligence, databases, social networks,distributedcomputing,Webengineering,informationsystems,natural language processing, soft computing, and human-computer interaction to d- cuss the major challenges and proposed solutions, success stories and failures, as well the visions that can advance the ?eld.

This volume contains papers from the technical program of the 6th European Semantic Web Conference (ESWC 2009), held from May 31 to June 4, 2009, in Heraklion, Greece. ESWC 2009 presented the latest results in research and applications of Semantic Web technologies. In addition to the technical research track, ESWC 2009 featured a tutorial program, a PhD symposium, a system demo track, a poster track, a number of collocated workshops, and for the ?rst time in the series a Semantic Web in-use track exploring the bene?ts of applying Semantic Web technology in real-life applications and contexts. Thetechnical researchpaper trackreceivedover250submissions.The review process was organized using a two-tiered system, where each submission was reviewed by at least three members of the Program Committee. Vice Program CommitteeChairsorganizedadiscussionbetweenreviewers,collectedadditional reviews when necessary and provided a metareview for each submission. During a physical Program Committee meeting, the Vice Program Committee Chairs together with the Program Chairs selected 45 research papers to be presented at the conference.

The World Wide Web has enabled the creation of a global information space comprising linked documents. As the Web becomes ever more enmeshed with our daily lives, there is a growing desire for direct access to raw data not currently available on the Web or bound up in hypertext documents. Linked Data provides a publishing paradigm in which not only documents, but also data, can be a first class citizen of the Web, thereby enabling the extension of the Web with a global data space based on open standards - the Web of Data. In this Synthesis lecture we provide readers with a detailed technical introduction to Linked Data. We begin by outlining the basic principles of Linked Data, including coverage of relevant aspects of Web architecture. The remainder of the text is based around two main themes - the publication and consumption of Linked Data. Drawing on a practical Linked Data scenario, we provide guidance and best practices on: architectural approaches to publishing Linked Data; choosing URIs and vocabularies to identify and describe resources; deciding what data to return in a description of a resource on the Web; methods and frameworks for automated linking of data sets; and testing and debugging approaches for Linked Data deployments. We give an overview of existing Linked Data applications and then examine the architectures that are used to consume Linked Data from the Web, alongside existing tools and frameworks that enable these. Readers can expect to gain a rich technical understanding of Linked Data fundamentals, as the basis for application development, research or further study. Table of Contents: List of Figures / Introduction / Principles of Linked Data / The Web of Data / Linked Data Design Considerations / Recipes for Publishing Linked Data / Consuming Linked Data / Summary and Outlook