“Heartbeat” is the first track from BTS' original soundtrack album for their mobile game, BTS World. Unlike the previous songs from the album, Heartbeat includes vocal parts from all 7 members.

The heartfelt track describes the desire for their fans' love and the feeling of their burning desire experienced by meeting their fans. In BTS World, the game raises the hypothetical reality of Bangtan never meeting and pursuing different lives, and “Heartbeat”, along with its music video, acts as an ode to what reality would’ve been had they not been BTS.

The track was pre-released in-game on the 26th of June, and an MV for the song was released on the 28th of June, 2 days after the first official appearance of the song.