Having surveyed the main concepts and standards for Linked Data, we now look in detail at SPARQL (SPARQL Protocol And RDF Query Language). As its name suggests, SPARQL is fundamentally a language for formulating queries, through which information can be retrieved from datasets. However, since it is targetted at datasets published on the World Wide Web, it also provides a protocol for specifying SPARQL commands. Moreover, in the latest version SPARQL 1.1 it has been extended to allow updating as well as querying, so that a SPARQL command can require data to be added, revised or deleted.

We also look in more detail at RDFS and OWL, which allow developers to formulate conceptual knowledge that can be exploited by automatic reasoning services in order to enhance the semantics of queries.