"October" is the seventh and title track from U2's 1981 album, October. It is a departure from U2's classic sound, as it is a quiet, almost instrumental piece. It was included as a hidden track on The Best of 1980-1990 compilation. It is the only track from October included in the compilation.

"October" reflects the spiritual turmoil of the band at the time it was written, during which three of the band's members were wrestling with whether being members of a rock band was consistent with their Christian beliefs. Lead singer Bono has said of "October":

U2 guitarist the Edge plays piano on the track despite having stopped playing piano as a teenager. Author John D. Luerssen describes the piano part as "one of U2's most enduring and meditative keyboard-steered melodies" and considers its somber mood as a reflection of the Edge's recent experience on tour playing in Europe under grey skies.

"October" made its live debut on 16 August 1981 and this performance featured extended, rambling lyrics from Bono that were never used again live. It was a setlist staple for much of the October Tour and followed "I Fall Down", another song from the October album that the Edge played on piano. However, it was omitted from the setlist at all 1982 dates where U2 supported the J. Geils Band.

At the first show of the War Tour's "Pre-Tour", "October" preceded "New Year's Day", a pairing that would later become a famous segue at U2 concerts in the 1980s. The pairing was utilised for all "Pre-Tour" concerts with known setlists, but for the first proper leg and the first two weeks of the second leg, U2 reverted to a pairing initially tried at two October Tour dates, where "October" segued into "Tomorrow".

In May 1983, "New Year's Day" returned to its position after "October" and the pairing was filmed for the Live at Red Rocks: Under a Blood Red Sky concert film. This pairing was played at almost every show on the Unforgettable Fire Tour and Joshua Tree Tour, typically as part of a greater combination that closed most main sets: "Bad", then "October", "New Year's Day", and finally "Pride (In the Name of Love)". At a few early Joshua Tree Tour shows, "With or Without You" was played between "October" and "New Year's Day". It is one of only three songs from October to be played live after the Unforgettable Fire Tour; the others are "Gloria" and "Scarlet".

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