Common characteristics include album-oriented music divided into compositions rather than songs, with usually complicated and long instrumental sections and symphonic orchestration. Its music was traditionally used within the context of concept records, and its lyrical themes tended to be "imaginative" and politically oriented. Differences have been identified between art rock and progressive rock, with art rock emphasizing avant-garde or experimental influences and "novel sonic structure", while progressive rock has been characterized as putting a greater emphasis on classically trained instrumental technique, literary content, and symphonic features. Compared to progressive rock, art rock is "more challenging, noisy and unconventional" and "less classically influenced", with more of an emphasis on avant-garde music. Similarities are that they both describe a mostly British attempt to elevate rock music to new levels of artistic credibility, and became the instrumental analog to concept albums and rock operas, which were typically more vocal oriented. Art rock can also refer to either classically driven rock, or to a progressive rock-folk fusion. Bruce Eder's essay The Early History of Art-Rock/Prog Rock states that "'progressive rock,' also sometimes known as 'art rock,' or 'classical rock'" is music in which the "bands [are] playing suites, not songs; borrowing riffs from Bach, Beethoven, and Wagner instead of Chuck Berry and Bo Diddley; and using language closer to William Blake or T. S. Eliot than to Carl Perkins or Willie Dixon." History 1960s Background The boundaries between art and pop music became increasingly blurred throughout the second half of the 20th century. The first usage of the term "art rock", according to Merriam-Webster Online Dictionary, was in 1968. As pop music's dominant format transitioned from singles to albums, many rock bands created works that aspired to make grand artistic statements, where art rock would flourish. As it progressed in the late 1960s – in tandem with the development of progressive rock – art rock acquired notoriety alongside experimental rock. Proponents The earliest figure of art rock has been assumed to be record producer and songwriter Phil Spector, who became known as an auteur for his Wall of Sound productions that aspired to a "classical grandiosity". According to biographer Richard Williams: "[Spector] created a new concept: the producer as overall director of the creative process, from beginning to end. He took control of everything, he picked the artists, wrote or chose the material, supervised the arrangements, told the singers how to phrase, masterminded all