In January 2016, S.M. Entertainment announced that they were to launch a digital music platform called SM Station, in which SM artists would release a new song every week.[3] "Rain" and its B-side track "Secret" served as the opening single of the project and were released on February 3, 2016.[4] "Rain" is described as a midtempo song with jazz and R&B sounds. Lyrically, it uses rain as a metaphor to describe memories of past love.[5][6]
Music video
The music video for "Rain" was filmed indoors, having the concept of Taeyeon in a "room of memories", missing a past lover. It alternate between black and white scenes of Taeyeon singing alone in front of a microphone, and colored scenes of her in a flooding room.[6][7] "Rain" was the most viewed music video by a South Korean act on YouTube in February 2016.[8]