Who Knew - Composition and Writing

Composition and Writing

"Who Knew" musically is a pop rock song, which features soft rock and ballad music. According to Musicnotes.com, which was published by Kobalt Music Publishing America, Inc., the song is set in the key A Major. Pink's vocal's span from E3 to D5. Lyrically, Pink had explained that the song is about "the death of friendship", as well as friends of hers who died as a result of drug overdoses. The song is about several people.

Billboard magazine, in its second review of the song (to accompany the U.S. re-release), called it "another cool, smart, plenty passionate melodic jewel about the death of a friend and/or friendship, with an instantly identifiable, quick-to-the-point, singalong track—maintaining Pink's stance as the smartest female millennium-era singer/songwriter, dazzling in star quality as alterna-pop's premier princess." The song features acoustic guitar, keyboards, drums, and electric guitars. Gottwald, Martin and Pink co-wrote another song on the album, "U + Ur Hand".