"All I Know" is a song written by American songwriter Jimmy Webb, first recorded by Art Garfunkel on his 1973 debut solo album, Angel Clare, released by Columbia Records. Instrumental backing was provided by members of the Wrecking Crew, L.A. session musicians. Garfunkel's version is the best known and highest-charting version, peaking at number nine on the Billboard Hot 100 and number one on the Easy Listening chart for four weeks in October 1973.

In his review for Allmusic, Joe Viglione wrote that Jimmy Webb's own version of the song, recorded for Ten Easy Pieces in 1996, had "none of the gloss" of Garfunkel's hit version, but more soul. Viglione continued:

The stark reading retains the elegance of the hit version while giving the melody a new setting, aided by the saxophone of Pat Perez and the backing vocals of producer Fred Mollin and arranger Matt McCauley. Jimmy Webb has a more earthy tone to his voice and, as beautiful as Art Garfunkel's rendition is, there's much more sincerity when the composer talk/sings it over his piano.

More recently, Webb invited Linda Ronstadt to join him in a duet version for his 2010 album Just Across the River. Ronstadt had just announced her retirement from singing when Webb sent her an email describing his new CD of duets. Webb asked if she would sing "All I Know" with him, with just a guitar backup. Ronstadt called him and said, "Damn it, you've gotten me interested in that song." Webb later recalled, "There was a poignancy to that moment ... because I didn’t know if she'd ever sing again. Her voice sounds elegantly beautiful on 'All I Know' ... I loved the meticulous way she covered my voice."

The song continues to appear in popular culture. It was recently featured in the season 2 finale and the series finale of the American drama series Nip/Tuck. The song was also used in a video montage in the ending credits of "The Grass Is Always Greener," Episode 12 in Season 3 of the American comedy-drama series Boy Meets World.

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