"Day Tripper" is a song by the English rock band the Beatles that was released as a double A-side single with "We Can Work It Out" in December 1965. The song was written primarily by John Lennon with some contributions from Paul McCartney and was credited to the Lennon–McCartney partnership. Both songs were recorded during the sessions for the band's Rubber Soul album. The single topped charts in Britain, Ireland, the Netherlands and Norway. In the United States, "Day Tripper" peaked at number five on the Billboard Hot 100 chart and "We Can Work It Out" held the top position.

The A-side and B-side are the two sides of phonograph records and cassettes, and the terms have often been printed on the labels of two-sided music recordings. The A-side usually features a recording that its artist, producer, or record company intends to be the initial focus of promotional efforts and radio airplay, with the aim of it becoming a hit record. The B-side is a secondary recording that typically receives less attention, although some B-sides have been as successful as, or more so than, their A-sides.