In 2001, Sir Tim Berners-Lee and others originated the idea of the semantic web, an Internet where web content is understandably and actionable by computers.
Since then, the W3C has lead the effort by coordinating and releasing a number of specifications and vocabularies to assist in the creation of the semantic web. This work has centered around the creation of graphs to represent data and their relationships through the following:
From The Linking Open Data Cloud
Unlike other types of data representation and storage technologies, RDF graphs are flexible enough to represent the knowledge systems of wide range of industries and disciplines.
Using RDF, OWL, and SKOS, communities can use their own vocabularies and then publish their data on the web to be used by other applications and organizations.
The fundemental data structure used in a RDF graph is the triple, a statement made up of three elements; a subject, a predicate, and an object.
Subjects are restricted to two types; International Resource Indicators (IRI), most commonly URLs or URIs, or can be Blank Nodes, an identifier placeholder unique to specific graph.
Predicates must IRI and define a relationship between a subject and an object.
Objects can be either an IRI, Blank Node, or a literal value.
Libraries, along with Museums and other Cultural Heritage Organizations, have started experimenting with putting information about their collections of physical and digital objects on the web as linked-data using RDF vocabularies.
BIBFRAME is a Library of Congress vocabulary that was released in 2012 to replace the legacy MARC21 format used by libraries for describing their collections.
Schema.org is an international effort to create a general vocabulary for representing entities and their relationships with other entities on the web is co-sponsored by the major search and technology companies like Google, Microsoft, Yandex, and Yahoo. This vocabulary has an extension mechanism for allowing industries and fields of study to describe their areas. Libraries are one of the first to provide a specific extension, available at bib.schema.org.