Every year ESWC brings together researchers and practitioners dealing with different aspects of semantic technologies. Following a successful re-launch in 2010 as a multi-track conference, the 8th Extended Semantic Web Conference built on the success of the ESWC conference series initiated in 2004. Through its extended concept this series seeks to reach out to other communities and research areas, in which Web semantics play an important role, within and outside ICT, and in a truly international, not just ‘European’ context. This volume contains the papers accepted for publication in key tracks of ESWC 2011: the technical tracks including research tracks, an in-use track and two special tracks, as well as the PhD symposium and the demo track.

Semantic technologies provide machine-understandable representations of data, processes and resources — hardware, software and network infrastructure — as a foundation for the provisioning of a fundamentally new level of functionality of IT systems across application scenarios and industry sectors. Using automated reasoning services over ontologies and metadata, semantically enabled systems will be able to better interpret and process the information needs of their users, and to interact with other systems in an interoperable way. Research on semantic technologies can benefit from ideas and cross-fertilization with many other areas, including artificial intelligence, natural language processing, database and information systems, information retrieval, multimedia, distributed systems, social networks, Web engineering, and Web science. These complementarities are reflected in the outline of the technical program of ESWC 2011; in addition to the research and in-use tracks, we furthermore introduced two special tracks this year, putting particular emphasis on inter-disciplinary research topics and areas that show the potential of exciting synergies for the future. In 2011, these special tracks focused on data-driven, inductive and probabilistic approaches to managing content, and on digital libraries, respectively.

The technical program of the conference received 247 submissions, which were reviewed by the Program Committee of the corresponding tracks. Each track was coordinated by Track Chairs and installed a dedicated Program Committee. The review process included paper bidding, assessment by at least three Program Committee members, and meta-reviewing for each of the submissions that were subject to acceptance in the conference program and proceedings. In all, 57 papers were selected as a result of this process, following comparable evaluation criteria devised for all technical tracks.