"One" is a song by Irish rock band U2. It is the third track from their seventh album, Achtung Baby (1991), and it was released as the record's third single on 24 February 1992. During the album's recording sessions at Hansa Studios in Berlin, conflict arose between the band members over the direction of U2's sound and the quality of their material. Tensions almost prompted the band to break up until they achieved a breakthrough with the improvisation of "One"; the song was written after the band members were inspired by a chord progression that guitarist the Edge was playing in the studio. The lyrics, written by lead singer Bono, were inspired by the band members' fractured relationships and the German reunification. Although the lyrics ostensibly describe "disunity", they have been interpreted in other ways.

"One" was released as a benefit single, with proceeds going towards AIDS research. The song topped the Irish Singles Charts, the Canadian RPM Top Singles chart and the US Billboard Album Rock Tracks and Modern Rock Tracks charts. It also peaked at number three in New Zealand, number four in Australia, number seven on the UK Singles Chart and numbers ten and three on the Billboard Hot 100 and Cash Box Top 100. In promotion of the song, the band filmed several music videos, although they were not pleased until a third was created.

The song was acclaimed by critics upon its release, and it has since been featured in polls as one of the greatest songs of all time. U2 has performed "One" at most of their tour concerts since the song's live debut in 1992, and it has appeared in many of the band's concert films. In a live setting, "One" is often used by the group to promote human rights or social justice causes, and the song lends its name to Bono's charitable organisation, the ONE Campaign. U2 re-recorded the song as part of a duet with R&B recording artist Mary J. Blige on her 2005 album The Breakthrough, and again for the band's 2023 album Songs of Surrender.

Writing and recording In October 1990, U2 arrived in Berlin on the eve of German reunification to begin the recording sessions for Achtung Baby at Hansa Studios. Expecting to be inspired by a "New Europe" and the reuniting city, the band instead found the mood to be bleak and soon conflict arose over their musical direction and the quality of their material. While bassist Adam Clayton and drummer Larry Mullen Jr. preferred a sound similar to U2's previous work, vocalist Bono and guitarist the Edge were inspired by European industrial and electronic dance music of the time and were advocating a change. The band also had difficulty developing demos and musical ideas into completed songs. Bono and the Edge believed the lack of progress was the fault of the band, while Clayton and Mullen believed the problem was the quality of the songs. Mullen said he "thought this might be the end" of the band.

Ultimately, a breakthrough in the sessions was achieved. While jamming on a song called "Sick Puppy"—an early version of "Mysterious Ways"—the band tried different chord progressions for the bridge. The jam stopped and the Edge tried playing them alone on an acoustic guitar, as "everyone was trying to decide if they were any good." At the suggestion of producer Daniel Lanois, the Edge played two separate sections sequentially. The band liked the way it flowed and decided to play it together. Speaking of the improvisation, the Edge said, "suddenly something very powerful [was] happening in the room." He added, "Everyone recognized it was a special piece. It was like we'd caught a glimpse of what the song could be." Soon afterwards, the band had developed the piece of music into "One". Bono recalls that "the melody, the structure—the whole thing was done in 15 minutes". He also stated that the lyrics "just fell out of the sky, a gift"; the concept was inspired by the band members' fracturing relationships, the German reunification, and Bono's scepticism of the hippie idea of "oneness". Bono later sent a note to the Dalai Lama declining an invitation to a festival called Oneness, incorporating a line from the song: "One—but not the same". The song's writing inspired the band and changed their outlook on the recording sessions. Mullen said the song reaffirmed the band's "blank page approach" to recording and reassured the band that all was not lost.

Following the song's initial improvisation, tapes of the recording sessions were delivered to assisting producer Brian Eno to gather his input; Eno spent extended periods of time away from the sessions before visiting to review songs, and he believed that distancing himself from the work allowed him to provide the band with a fresh perspective on their material each time he rejoined them. The band were rather anxious about the quality of their material, but when Eno arrived in Berlin, they were surprised to hear that he liked most of the tapes. However, as Bono recalls, Eno said, "There's just one song I really despise, and that's 'One'." Eno felt that they needed to deconstruct the song.

The band returned to Dublin in 1991 to record at the "Elsinore" mansion on the Dalkey coastline. The band continued to work on the song there, adding various overdubs, but not finding a mix they were satisfied with. The Edge thought that they had the foundation for the song, but that it needed "foreground". Eno interceded, explaining to the group that "One" was among the sessions' tracks in which "The song has gone, whatever it is you liked about this song is not there anymore", and that the track had "disappeared under layers of overdubs". He created his own mix, which gave the band a better idea of an arrangement they liked. Eno wanted the band to remove the melancholy elements of the song and persuaded them to remove the acoustic guitar from the song. He also worked with Lanois and the Edge to "undermine the 'too beautiful' feeling", which is why they added the "crying guitar parts that have an aggression to them". While working with Lanois in the studio on a vocal overdub, Bono suggested Lanois "play a little guitar part to try and juice [him] up". Lanois subsequently took Bono's green Gretsch guitar and played a hammer-on part that was included in the final version of the song.

Flood, the sessions' engineer, was unconvinced by the song's mix, saying he "was the nagging doubter. I always felt it was a bit straight, until we did the final mix." The final mix was completed at Windmill Lane Studios in September 1991 on the last night of the album's recording sessions, when some last minute additions were made. Bono did not like a line in the vocals and spent most of the day re-recording it. Later, after the song's mix had just been completed by the production team, the Edge came up with a guitar part he wanted to add to the song's end near the lyric "Love is a temple". After convincing the production team to allow the addition, the Edge played the part once and had it mixed in ten minutes later.

Composition "One" is a rock ballad played in a time signature at a tempo of 91 beats per minute. The verse follows a chord progression of Am–D5–Fmaj7–G while the chorus follows C–Am–Fmaj7–C. Note: Software required to view the page.

Bono described the song's theme as such: "It is a song about coming together, but it's not the old hippie idea of 'Let's all live together.' It is, in fact, the opposite. It's saying, We are one, but we're not the same. It's not saying we even want to get along, but that we have to get along together in this world if it is to survive. It's a reminder that we have no choice". The Edge described it on one level as a "bitter, twisted, vitriolic conversation between two people who've been through some nasty, heavy stuff".McCormick (2006), pp. 221, 224. On another level, he suggested that the line "we get to carry each other" introduces "grace" to the song and that the wording "get to" (instead of "got to") is essential, as it suggests that it is a privilege to help one another, not an obligation. The band have been told by many fans that they played the song at their weddings, prompting Bono to respond, "Are you mad? It's about splitting up!" There was some speculation that the song described a conversation between a father and his HIV-positive gay son, based on the connection of the song to David Wojnarowicz, a gay artist who died of AIDS.Stokes (2005), pp. 98–100 In 2005, Bono said "It's a father-and-son story. I tried to write about someone I knew who was coming out and was afraid to tell his father. It's a religious father and son."

Release "One" was released as the album's third single on 24 February 1992 as a benefit single, with all of the band's royalties being donated to different AIDS research organisations for each country in which the single was released. The group's manager Paul McGuinness commented on their decision: "The band feels that [AIDS] is the most pressing issue of the day, and we really have to focus people's attention to the AIDS plague that has been with us for 10 years." To promote safe sex, U2 sold condoms bearing the album title Achtung Baby at their Zoo TV Tour concerts. The cover of the single release is a photograph by David Wojnarowicz. The photograph depicts buffaloes falling off a cliff after being chased by Native American hunters. The single's liner notes explain that Wojnarowicz "identifies himself and ourselves with the buffalo, pushed into the unknown by forces we cannot control or even understand".

The single reached number seven on the UK Singles Chart, number ten on the US Billboard Hot 100, number three on the US Cash Box Top 100, and number one on the US Album Rock Tracks and Modern Rock Tracks charts.

Music videos Three music videos were created for "One". The first, directed by Anton Corbijn, was filmed in Berlin and features the band members performing at Hansa Studios interspersed with footage of Trabants (an East German automobile they became fond of as a symbol for a changing Europe) and shots of them dressed in drag. Bono explained that the idea to crossdress "had been based on the idea that if U2 can't do this, we've got to do it!", and it was fostered by the group's experiences dressing in drag for the Carnival of Santa Cruz de Tenerife.Flanagan (1996), p. 58 However, the band pulled the video, fearing the single's status as an AIDS benefit would result in critics finding AIDS-related interpretations of the video. The Edge explained, "We didn't want to be involved in putting back the AIDS issue into the realm of sexuality... It wasn't worth the risk of people imagining we were saying something about the AIDS issue through the drag footage, which was totally not what we were trying to say."Cogan (2008), p. 27

The second video was directed by Mark Pellington. It comprises images of blooming flowers, the title word in several languages, and slow-motion footage of buffaloes running, leading up to Wojnarowicz's "Falling Buffalo" photograph. Much like for the first video, the band did not believe Pellington's video would be good for promoting the single.Flanagan (1996), p. 55

The group filmed a third video in an attempt to appeal to a broader audience. It was directed by Rattle and Hum director Phil Joanou and was primarily filmed in early March 1992 at Nell's, a Manhattan nightclub.McGee (2008), p. 145 The video depicts Bono sitting at a table smoking a cheroot and drinking beer, interspersed with footage of the band performing in concert. While Bono was filmed, the rest of the band, along with models and transgender women, attended a party in the basement, awaiting their turns to be filmed. However, they were never called to the set and by 3 a.m., they realised that the video was to focus on Bono.Flanagan (1996), pp. 56–57

Reception