This page is designed to help you test the OpenLink Virtuoso SPARQL protocol endpoint.
Consult the Virtuoso Wiki page describing the service or the Online Virtuoso Documentation section RDF Database and SPARQL.
There is also a rich Web based user interface with sample queries. You can access it at: /isparql.
SPARQL is the W3C''s declaritive query-language for Graph Model Databases and Stores.
As is the case with regards to SQL for relational databases and XQUERY for XML databases, SPARQL is database and host operating system independent.
The development and evolution of this standard is overseen by the SPARQL Working Group within W3C and while parts of the language are still in active development, it is fully documented and publicly available.