|Stylistic origins||Psychedelic rock, garage rock|
|Cultural origins||Late 1960s United States|
|Typical instruments||Electric guitar (usually with guitar effects - distortion, fuzzbox, phaser, etc.) - bass guitar - electronic organ - drums|
|Derivative forms||Heavy metal, space rock, stoner rock|
|San Francisco, California|
Acid rock is a form of psychedelic rock, which is characterized by long instrumental solos, few (if any) lyrics and musical improvisation. Tom Wolfe describes the LSD-influenced music of The Doors, The Jimi Hendrix Experience, Pink Floyd, Iron Butterfly, Big Brother & The Holding Company, Cream, Vanilla Fudge, Jefferson Airplane, Ultimate Spinach, Black Sabbath, Blue Cheer, Quicksilver Messenger Service, The Great Society, Stone Garden and the Grateful Dead as "acid rock" in his book about Ken Kesey and the Acid Tests, The Electric Kool-Aid Acid Test.
"Acid rock" also refers to the subset of psychedelic rock bands that were part of, or were influenced by, the San Francisco Sound, and which played loud, "heavy" music featuring long improvised solos.
History and use of the term 
Acid rock got its name because it served as "background" music for acid trips in underground parties in the 1960s (e.g. the Merry Pranksters' "Acid Tests"). ("Acid" is a slang term for LSD.) In an interview with Rolling Stone, Jerry Garcia quoted Grateful Dead band member Phil Lesh stating, "acid rock is what you listen to when you are high on acid." Garcia further stated there is no real psychedelic rock and that it is Indian classical music and some Tibetan music that are examples of music "designed to expand consciousness." The term "acid rock" is generally equivalent to psychedelic rock. Rolling Stone magazine includes early Pink Floyd as "acid-rock". In June 1967 Time magazine wrote, "From jukeboxes and transistors across the nation pulses the turned-on sound of acid-rock groups: the Jefferson Airplane, The Doors, Moby Grape". In 1968 Life magazine referred to The Doors as the "Kings of Acid Rock".
When hard rock and heavy metal became prominent in the early and mid-1970s, the phrase "acid rock" was sometimes mistakenly applied to these genres. Over time, these bands such as Alice Cooper fell in under the term "heavy metal" which replaced "acid rock" for these styles of music.
- Acid rock at Allmusic.
- Allmusic Stone Garden Review of album released in 2002 of 1960s music by band of same name
- Wolfe, Tom (1968). The Electric Kool-Aid Acid Test. Black Swan. p. 223. ISBN 0-552-99366-2.
- Gilliland, John (1969). "Show 41 - The Acid Test: Psychedelics and a sub-culture emerge in San Francisco. [Part 1] : UNT Digital Library" (audio). Pop Chronicles. Digital.library.unt.edu. Retrieved 2011-04-29.
- Lucky, Jerry (2003). The Psychedelic Rock Files. Collector's Guide Publishing Inc. p. 262. ISBN 1-896522-97-1.
- Rolling Stone Magazine Staff. "Talking with the Legend of Rock and Roll (Jerry Garcia)". The Rolling Stone Interviews: 1967-1980. p. 195. ISBN 0-312-03486-5.
- "Pink Floyd Biography". Rollingstone.com. Portions of this biography appeared in The Rolling Stone Encyclopedia of Rock & Roll (Simon & Schuster, 2001). Andy Greene contributed to this article.
- "Youth: The Hippies". Time (June 7, 1967).
- Powledge, Fred. "Wicked Go The Doors". Life (April 12, 1968).
- Buckley, Peter (2003). The Rough Guide to Rock. Rough Guides. p. 224. ISBN 1-84353-105-4.