US singer Bob Dylan has been awarded the 2016 Nobel Prize for Literature, becoming the first songwriter to win the prestigious award.
The 75-year-old rock legend received the prize "for having created new poetic expressions within the great American song tradition".
The balladeer, artist and actor is the first American to win since novelist Toni Morrison in 1993.
President Obama said the honour was "well-deserved".
"Congratulations to one of my favourite poets," he wrote on Twitter.
Sara Danius, permanent secretary of the Swedish Academy, said Dylan had been chosen because he was "a great poet in the English speaking tradition".
"For 54 years now he's been at it reinventing himself, constantly creating a new identity," she told reporters in Stockholm.
The singer is due to perform later at the Cosmopolitan hotel in Las Vegas.
Dylan - who took his stage name from the poet Dylan Thomas - had long been tipped as a potential prize recipient.
Few experts, though, expected the academy to extend the award to a genre such as folk rock music.
Former Poet Laureate Sir Andrew Motion is among those to have previously praised Dylan's lyrics, saying his songs "work as poems".
"They have often extremely skilful rhyming aspects to them," he told the BBC. "They're often the best words in the best order."
Analysis by Colin Paterson, entertainment correspondent
Bob Dylan - the first person to win a Nobel Prize the same day as he plays a gig in Las Vegas.
What makes a man who has only ever written three books a suitable winner of the Nobel Prize for literature?
Bob Dylan arguably made the lyrics more important than the music.
Last Friday Dylan supported The Rolling Stones at the Desert Trip Festival in California and his set included Rainy Day Women #12 & 35 from that very album.
It is a song with the refrain "everybody must get stoned," leading to decades-long debates about whether it deals with Old Testament-style punishment or a call to smoke cannabis. Or most probably both.
Few would argue that is one of his finest lyrics, but it does demonstrate the mixture of political questioning, religious exploration and interest in humanity which has been woven through his work for more than 50 years and has secured him this award.
The result also demonstrates a real change for the prize. In 112 years, no songwriter has ever won before.
The decision elevates song lyrics to being on a critical par with literature, poetry and playwriting. It's a big step away from the self-perpetuating intellectualism and elitism for which the award had been criticised.
Dylan was born Robert Allen Zimmerman in 1941 and began his musical career in Minnesota before heading for New York.
Much of his best-known work dates from the 1960s, when he became an informal historian of America's troubles.
Blowin' in the Wind and The Times They are A-Changin' were among anthems of the anti-war and civil rights movements.
His move away from traditional folk songwriting, paired with a controversial decision to "go electric" proved equally influential.
Dylan's many albums include Highway 61 Revisited in 1965, Blonde on Blonde in 1966 and Blood on the Tracks in 1975.
Since the late 1980s he has toured persistently, an undertaking that has been dubbed by some the "Never-Ending Tour".
Recent winners of the Nobel Prize for Literature:
2015: Svetlana Alexievich (Belarus)
2014: Patrick Modiano (France)
2013: Alice Munro (Canada)
2012: Mo Yan (China)
2011: Tomas Transtromer (Sweden)
The estate of late Beatle George Harrison, which whom Dylan performed as part of the Travelling Wilburys, is among those to tweet its congratulations.
Simply Red's Mick Hucknall said he was the "greatest living poet", while Eurythmics' Dave Stewart welcomed the news by saying: "I love this."
Writer Sir Salman Rushdie also praised Dylan's win, saying: "From Orpheus to Faiz, song & poetry have been closely linked. Dylan is the brilliant inheritor of the bardic tradition. Great choice."
But Trainspotting author Irvine Welsh voiced his displeasure on Twitter, saying: "I'm a Dylan fan, but this is an ill conceived nostalgia award wrenched from the rancid prostates of senile, gibbering hippies."
US novelist Jodi Picoult also conveyed ambivalence, accompanying a message saying she was "happy" for Dylan with the Twitter hashtag "#ButDoesThisMeanICanWinAGrammy?"
The award will be presented alongside this year's other five Nobel Prizes on 10 December, the anniversary of prize founder Alfred Nobel's 1896 death.
The award announcement came on the same day that the death of Italian playwright Dario Fo - winner of the Nobel Prize for Literature in 1997 - was announced.