This document discusses the history and characteristics of progressive/art rock music. It notes that the genre emerged in the late 1960s following albums like Sergeant Pepper's Lonely Hearts Club Band, peaked commercially in the early 1970s, and declined in popularity by the late 1970s. Key progressive rock bands included Yes, Genesis, Emerson Lake and Palmer, Jethro Tull, King Crimson, and Pink Floyd. The genre was known for extended instrumental sections, blending styles beyond blues/rock, and drawing on classical music influences.