The key instrument used in hard rock is the guitar. Electric and bass guitars are used in hard rock songs, sometimes for long solo riffs. The lead singer of a hard rock band will typically play one of these guitars. Additionally, drums provide a critical back beat for hard rock music.
A number of bands and artists helped popularize the music dating back to the 1960s. Jimi Hendrix was one of the first guitarists associated with hard rock. Other bands, like Led Zeppelin, AC/DC, The Stooges, Van Halen and Foreigner, were also critical in the success of hard rock music. These groups have made hard rock a popular genre to this day.
Hard rock formed from many previous genres, and it also gave way to a number of spin-offs. Hard rock music was a supreme influence in future styles, including heavy metal, grunge rock, emo and alternative music. Heavy metal is especially similar to hard rock, the primary difference being the lack of harmonious beat in metal music.