Acid rock is a loosely defined type of rock music that evolved out of the mid-1960s garage punk movement and helped launch the psychedelic subculture. The style is generally defined by heavy, distorted guitars, lyrics with drug references, and long improvised jams. Its distinctions from other genres can be tenuous, as much of the style overlaps with '60s punk, proto-metal, and early heavy, blues-based hard rock. The term “acid rock” is sometimes colloquially used interchangeably with “psychedelic rock", but the two terms are also generally differentiated as referring to distinct yet related genres, with acid rock often cited as a heavier, louder, rawer, or harder subgenre or sibling of psychedelic rock.
