Hard rock is a loosely defined genre of rock music which has its earliest roots in mid-1960s garage, blues rock and psychedelic rock. It is typified by a heavy use of distorted electric guitars, bass guitar, drums, pianos, and keyboards. One of the major influences of hard rock is blues music. American and British rock bands began to modify rock and roll, adding to the standard genre harder sounds, heavier guitar riffs, bombastic drumming and louder vocals. Read more on Last.fm.