When used in libraries, archives and museums, Linked data allows us to connect pieces of data that were not previously connected. For example, linked data would allow you to trace a person in a photograph on one website, to a postcard on another completely different site, to a diary on yet another one. Based on technologies of the Semantic Web, it also allows us to represent specific relationships between people, places and things, indicating, for instance, whether that person in the picture wrote the diary or was mentioned in it, whether the postcard was sent to them, written by them, or mentioned them. Enriching data through linkages allows us to connect information from different sources, resulting in increased visibility of collections and linked knowledge.
Linked Data and the Semantic Web are about teaching computers the meanings of individual terms using what's called a URI as a unique identifier, and stating the relationships between terms as RDF triples. The specific connections among those relationships are defined in structured vocabularies called ontologies. Using the three elements of URIs, RDF triples, and ontologies, computers can then infer further relationships and connections beyond those explicitly stated. For example, in a genealogy context, I can state that my sister has a daughter named “Alyssa”; a computer can then infer that Alyssa is my niece, and that I am Alyssa’s aunt.