Hard Rock

A loosely defined subgenre of rock music which has its earliest roots in mid-1960s garage rock, blues rock and psychedelic rock. It is typified by a heavy use of distorted electric guitars, bass guitar, drums, and often accompanied with pianos and keyboards. Hard rock developed into a major form of popular music in the 1970s, with bands such as Led Zeppelin, The Who, Deep Purple, Aerosmith, AC/DC, and Van Halen, and reached a commercial peak in the mid to late 1980s. The glam metal of bands like Bon Jovi and Def Leppard and the rawer sounds of Guns N' Roses followed up with great success in the later part of that decade, before losing popularity with the commercial success of grunge and later Britpop in the 1990s. Hard rock has sometimes been labelled cock rock for its emphasis on overt masculinity and sexuality and because it has historically been predominately performed and consumed by men: in the case of its audience, particularly white, working-class adolescents. Hard rock maintained a bluesy rock and roll identity, including some swing in the back beat and riffs that tended to outline chord progressions in their hooks.

Source: http://en.wikipedia.org/wiki/Hard_rock