Summary

SPARQL is a query language and protocol used for retrieving and manipulating data stored in Resource Description Framework (RDF) format. It’s a tool integral in Semantic Web and Linked Data projects, enabling intricate data searching across disparate databases.

ELI5

Imagine you’re in a massive library, where all books are scattered, and there’s no universal way they’re described or connected. You’ve a magical language (SPARQL) to ask the library for specific books or facts - maybe you want ‘All books where the hero has a pet dog and author lives in London’. SPARQL helps find these, even if this information is in different places or formats.

In-depth explanation

SPARQL (SPARQL Protocol and RDF Query Language) is a query language and a protocol for databases able to store data in RDF (Resource Description Framework) format. Similar to how SQL is used for relational databases, SPARQL is utilized for querying and manipulating RDF datasets.

RDF, a key underpinning of Semantic Web vision, allows for representing information about resources in a graph format. It describes resources in triples—subject, predicate, and object format. Resources and statements about them are represented as web resources with URIs, promoting interoperability across the internet.

SPARQL is designed around this RDF structure. A SPARQL query can consist of several ’triple patterns’ which match the subject-predicate-object structure of RDF. It allows expressing complex queries against RDF data, selecting and combining data from different sources, and transforming it into the format required by users or applications.

SPARQL comes with various forms of queries: SELECT, CONSTRUCT, ASK, and DESCRIBE. SELECT is used most often, returning a table of results similar to SQL. CONSTRUCT transforms data into more RDF, ASK returns a yes/no response, and DESCRIBE returns an RDF graph.

SPARQL also supports data manipulation operations (INSERT, DELETE, etc.), advanced querying (aggregation, grouping, etc.), and expressive pattern matching via its graph pattern capabilities.

With RDF standardizing the way data is represented, OWL enabling logical reasoning, and SPARQL providing complex querying - the combination empowers Semantic Web and Linked Data endeavors, enhancing discovery, integration, and reuse of data.

Resource Description Framework (RDF), World Wide Web Consortium (W3C), Linked Data, Semantic Web, Ontology Web Language (OWL), Triplestore, Uniform Resource Identifier (URI), SQL, Graph Database