The lyrics were written by lead vocalist Bono as a love song for his wife, Ali, after he had a nightmare that he had destroyed their relationship.

[1] Lead vocalist Bono referred to the song as "defiant joy", something that he and the Edge said was more important than ever in the "difficult times" in which they were living.

[2] The song first emerged in August 2016 as an electronic dance remix by Norwegian DJ Kygo, which he played during his performance at the Cloud 9 Festival.

"[8] The song title was inspired by a comment that Irish media personality Eamon Dunphy made to Bono in a Dublin bar, telling him the best thing about him was Ali.

[12] After listening to it, the group decided to revert to the song's original, simpler guitar-driven arrangement, using what the Edge called "the primary colors of U2" of guitar, drums, and bass.

The image evokes the cover art of the group's 1998 compilation album The Best of 1980–1990, which showed the younger brother of Guggi, a friend of Bono, wearing a similar helmet.

[15] On 7 September, the band performed the song on The Tonight Show Starring Jimmy Fallon[16] before debuting it live three days later at a concert in Indianapolis on the Joshua Tree Tour 2017.

The band said the video is "a visual tapestry of tribute to New York and a serenade to the city's iconic symbols of American compassion and liberty".