The most common examples of electronic media are video recordings, audio recordings, slide presentations, CD-ROM and online content. The term also incorporates the equipment used to create these recordings or presentations; television, radio, telephone, computer. Much of the theory surrounding the use of electronic media by artists is based on Walter Benjamin's seminal essay of 1936, The Work of Art in the Age of Mechanical Reproduction, which discussed the democratisation of art, freed from its confines as a unique entity thanks to the development of photographic reproduction and forms such as cinema, where there is no unique original.