Classic rock is a US radio format which developed from the album-oriented rock (AOR) format in the early 1980s. In the United States, the classic rock format comprises rock music ranging generally from the mid-1960s through the mid 1990s, primarily focusing on commercially successful blues rock and hard rock popularized in the 1970s AOR format. The radio format became increasingly popular with the baby boomer demographic by the end of the 1990s.