This document provides an overview of linked data and semantic applications for libraries. It discusses the key concepts of linked data including URIs, RDF, ontologies and the semantic web. It then outlines some of the core technologies that enable linked data such as XML, RDF, RDF Schema and OWL. The document also reviews current trends and implementations of linked data including projects from DBPedia, BBC, Google and OCLC. Finally, it discusses why linked data is important for libraries by allowing library resources to be more discoverable on the web and enabling new applications using library metadata.