This book presents thoroughly arranged tutorial papers corresponding to lectures given by leading researchers at the Second International Summer School on Reasoning Web in Lisbon, Portugal, in September 2006. Building on the predessor school held in 2005 and published as LNCS 3564, the ten tutorial lectures presented provide competent coverage of current topics in semantic Web research and development.

This book constitutes the refereed proceedings of the 4th European Semantic Web Conference, ESWC 2007, held in Innsbruck, Austria, in June 2007. Coverage includes semantic Web services, ontology learning, inference and mapping, social semantic Web, ontologies, personalization, foundations of the semantic Web, natural languages and ontologies, and querying and Web data models.