Album-oriented rock
Album-oriented rock (AOR, originally album-oriented radio) is a radio format created in the United States in the late 1960s that focuses on the full repertoire of rock albums and is currently associated with classic rock.
The format arose when US FM radio stations decided to play tracks by hard rock and progressive rock artists. In the mid-1970s, AOR was characterized by a layered, mellifluous sound and sophisticated production with considerable dependence on melodic hooks. By the early 1980s, research and formal programming had honed the format's commercial appeal, leading to tremendous popularity. In the early 1980s, the abbreviation AOR shifted to "album-oriented rock", meaning music in the classic rock genre recorded in the late 1960s and 1970s.
The term is also commonly conflated with "adult-oriented rock", a radio format that also uses the initialism "AOR" and covers not only album-oriented rock but also album tracks and "deep cuts" from other rock genres, such as soft rock and pop rock.