From Science Europe Data Glossary
Definition: linked data is a term used to describe a recommended best practice for exposing, sharing, and connecting pieces of data, information and knowledge on the Semantic Web.
Explanation: linked data refers to data published on the web in such a way that it is machine-readable, that its meaning is explicitly defined, that it is linked to other external data sets, and that in turn it can be linked to from external data sets. Linked data is expressed in what are called RDF triples. A triple such as "the sky has the color blue" consists of an entity (sky), attribute (color) and value (blue). The Resource Description Framework (RDF) is a family of World Wide Web Consortium (W3C) specifications originally designed as a metadata data model. The Semantic Web provides a common framework that allows data to be shared and reused across application, enterprise, and community boundaries.