Hello", a trap song performed by Nayeon, Momo, and Chaeyoung, [1] has lyrics devoted to Twice's "powerful and cool appearance onstage".

At the end of the " The Feels" music video, it was revealed that TWICE would be releasing a full studio album in November 2021.

The title has dual meanings: 'when ONCE and TWICE meet, it becomes love (<3)' by using the initials of ONCE, the official name of TWICE's fandom, and TWICE, and it is the third full-length album ('1+2=3') by using English words. Following Eyes Wide Open (2020), Formula of Love: O+T=<3 is Twice's third Korean-language studio album.

In an interview with the Associated Press, Jihyo revealed that the death of a houseplant was her inspiration for writing the song, and it was written from the plant's perspective, "seeing its owner walking in and out of the room and ignoring it". Moreover, on other Billboard charts, the album peaked at numbers 7, 2, and 1 on Tastemakers, [48] Top Album Sales, [49] and World Albums, [50] respectively. The tenth track, "Cactus" ( 선인장), written and composed by Jihyo, is a ballad that incorporates pop-rock elements. The track “Candy” was performed on TWICE’s 6th Anniversary celebration H6ME PARTY with 6NCE, on October 29, 2021, before its official release.Formula of Love: O+T=<3 opens with its title track, " Scientist", a song blending elements of dance-pop and deep house, and featuring '80s-inspired synths with "groovy" bass lines in its production. It consists of sixteen tracks, including the group's first English single " The Feels" and lead single " Scientist".

At the end of the music video of Twice's first English single, " The Feels", a full-length album scheduled to be released in November 2021 was teased. Momo explained the meaning behind the lyrics, saying "it is a sad story about wanting to make the day you break up with someone the best, perfect day.The song's lyrics are about playful pushing and pulling in a relationship "to bring the other person closer".