Hard rock is a form of rock and roll music that finds its closest roots in early 1960s garage rock. Budgie, AC/DC, The Stooges, MC5, Living Colour, Prong, Skid Row, Jimi Hendrix and Deep Purple are easy to find examples of early hard rock. Van Halen (up to 1984) typifies the energy of this genre. The genre achieved maximum popularity between 1969 and 1985.
A "classical" hard rock band is usually a four person lineup:
Many bands have two guitar players, and, optionally, a synthesizer player.
Hard Rock is usually, but not always written with major key song construction, as opposed to heavy metal, which is often minor key oriented. There is a heavy reliance on the pentatonic scale for most elements of song construction, and fifths are often substituted for traditional chords. Chord progressions are commonly associated to 1-4-5 degrees of the scale, as in rock & roll.
It is typified by a bright, trebly overdrive distortion effect on the guitars, lending to its overall sound. Drums can range from 100-150 Beats Per Minute, with 120 BPM being typical. Bass is usually round & warm sounding.
The guitar solo is very important part of a hard rock song, and leads to the credibility of the song just as much as the lyrics and vocal melodies do. Songs are generally hook laden, and consist of:
Jazz, Blues, and rock & roll were the roots of this style, as with heavy metal.
Punk rock, Gothic rock, Industrial music, funk, and fusion also claim these roots, but branch off at different points, eliminating elements that are considered unnecessary, and adding elements to typify their genre. Interestingly, death metal and industrial music also incorporate a march rhythm.
See also: IRIS