[3][4][5][6] Pledis Entertainment posted a 40-second trailer video on October 5, 2020, which revealed that Seventeen would be releasing a new EP Semicolon the same month.

Like the very punctuation, ; [Semicolon] represents a brief pause and moment to take a breath, exchanging laughter with one another even amidst the hardships of the generation.

[1][11] The song incorporates strong brass sound, "chipper" finger-snaps, cheerful beats and jazz-inflected piano harmony in its production and Asian instruments in its bridge.

[13][10] The third track, "Light A Flame" (마음에 불을 지펴) incorporates Latin-inflected bossa nova jazzy rap with an orchestral pitch.

[4][13] The album concludes with the midtempo mellow acid jazz and synth ballad, "All My Love" (겨우), featuring '90s nostalgic hooks.

[21] The '20s themed visual is a cross-over between Murder on the Orient Express and Beyoncé's 2006 movie The Pink Panther, and features the band members sporting retro-suits in underground poker clubs and smoky pool bars.

[9] A few hours prior to the album release, the band held a press conference, which was broadcast online through YouTube.

[20] Seventeen began promoting the album with televised live performances on several South Korean weekly music programs, starting with Mnet's M!