Resource Description Framework (RDF) is a W3C Standard model for data interchange used to represent interconnected data. It is an expressive domain-independent data model for Linked Data and the Semantic Web used to model and represent real-word or abstract concepts as information resources on the web. It is a machine-readable format that is interoperable across different architectures described by a semantic schema or ontology. The basic structure of RDF is called a triple - subject x predicate x object. This is akin how sentences in the english language are constructed: subject-verb-object. Triples can be depicted in a graph form, where the subject and object of a triple are the nodes, whilst the predicate is the edge.
Let us consider the following sentence as an example: Jeremy is born in Birkirkara. This sentence can be represented by an RDF statement with the following structure: Jeremy is a subject resource, the predicate (property) born in, and an object of Birkirkara, which is another resource.
A group of triples of the same subject is called a resource, which is identified by a unique resource identifier (URI). In short, RDF is a flexible model that enables effective data integration and interlinking from different sources, giving semantic meaning to resources. A collection of these resources make up an RDF dataset, or a Knowledge Graph. RDF provides formal semantics allowing humans and machines to interpret and understand data in a semantically meaningful and unambiguous way. RDF data can be queried with the SPARQL protocol.
There are a number of serialisation formats that can be used to represent the RDF data model. The RDF/XML format gets its inspiration form XML, however this could be cumbersome to read, especially when the RDF dataset is large. Other serialisation formats include Turtle, RDFa (used as embedded HTML), and JSON-LD (JSON structure with semantic context embedded).
