"Diary" is a song by American singer-songwriter Alicia Keys from her second studio album, The Diary of Alicia Keys (2003). Written by Keys and Kerry Brothers, Jr. and produced by Keys, the song features the American group Tony! Toni! Toné! on bass, piano, guitar, organ and Wurlitzer, while Jermaine Paul provides uncredited additional vocals. It was released on May 24, 2004, as the album's third single. At one time, "Diary" had been released as a double A-side with "If I Ain't Got You".

Jeremiah Jermaine Paul is an American R&B singer-songwriter. He is the winner of season 2 of American talent competition The Voice. Prior to his stint on The Voice, he provided vocals on Alicia Keys' Grammy-nominated song "Diary" from her 2003 album, The Diary of Alicia Keys. Paul was a member of the short-lived R&B group 1Accord, which was signed to Shaquille O'Neal's T.W.Is.M. Records.