Hard rock is strongly influenced by blues music; the most frequently used scale in hard rock is 
the pentatonic, which is a typical blues scale. Departing from earlier acoustic based blues, hard rock makes use of more modern instruments such as electric guitars, drums and electric bass. A notable departure from traditional blues forms is that hard rock is seldom restricted to the I, IV, and V chords prevalent in twelve or sixteen bar blues, but includes other chords, typically major chords rooted on tones of the minor scale. Hard Rock Music got originated form 1960s. Now hard rock have been in progeress very well. there were many hard rock bands made during these periods till now. Among them some are AC/DC, Aerosmith, Audioslave, Bad company, Bon jovi, Deep Purple, Guns N' Roses, Nickelback, Union and so on...
