SPARQL

SPARQL is the query language and protocol for the Resource Description Framework (RDF), the standard model for data interchange on the Semantic Web. It enables applications to retrieve and manipulate data stored in RDF graphs and can operate over multiple named graphs or remote endpoints.

SPARQL supports four query forms: SELECT, which returns tabular results; CONSTRUCT, which produces RDF graphs; ASK, which returns a boolean; and DESCRIBE, which provides an RDF description of resources. Queries are built from graph patterns using triples, together with operators such as OPTIONAL, UNION, FILTER, and, in later versions, property paths. Features include aggregation (GROUP BY, HAVING), ordering, and limits.

SPARQL is built around the SPARQL Protocol, an HTTP-based protocol used to send queries and receive results in formats such as XML, JSON, CSV, or RDF. SPARQL Update provides commands to modify RDF data, including INSERT DATA, DELETE DATA, and more complex forms. Federated queries allow querying over multiple endpoints using SERVICE.

Applications include knowledge graphs, data integration, digital libraries, and open data portals. SPARQL endpoints enable data sharing and interoperability across organizations and systems, supporting both read and write operations depending on authorization and endpoint capabilities.

SPARQL 1.0 became a W3C Recommendation in 2008; SPARQL 1.1, published in 2013, added Update, Federated Query, and Graph Store Protocol enhancements. Today, SPARQL remains a core standard for querying RDF stores and knowledge graphs, with multiple implementations and broad support across database systems and data portals.