"Birthday" is the debut single of Canadian-Dutch-Korean singer-songwriter Jeon Somi. The song was released by The Black Label on June 13, 2019. Background and release On November 21, 2018, News1 reported that Somi was working on new music with the goal of making her solo debut in March 2019. On February 23, 2019, it was reported that the debut date would be May and that she will be debuting with a song produced by Teddy, also confirming that the recording process was completed and was currently preparing to shoot the accompanying music video. It wasn't confirmed if the release will be a single or an EP. Shortly after, The Black Label confirmed that Somi will debut in May and that the song produced by Teddy was finished, but the format of the release was not confirmed. Two days later, the agency confirmed that Somi will debut on May 1. On April 29, it was reported that her debut date was delayed due to internal issues in her agency and the anticipated date of her debut is now late May. It was also cited that the delay was in order to consider the quality of the album. Later on that day, the agency stated that "her album production is complete but the timing of her debut has not been decided yet." It was also added that the music video was not filmed yet. On May 1, The Black Label released a promotional poster of Somi with her name along with "Debut Coming Soon" written on it. On May 10, the second promotional poster was released, also having the same phrase from the previous photo written on it. Ten days later, The Black Label released the third promotional poster of Somi with a mysterious date written on it, confirming her debut the next month. On June 7, another promotional poster was released, revealing the title track "Birthday" and its credits. The next day, the full tracklist of two songs was released. On June 13, 2019, "Birthday" was released alongside its music video. Composition "Birthday" was written by Teddy, Brother Su, Bekuh Boom and Danny Chung; composed by Teddy, 24, Bekuh Boom and Somi; and arranged by 24 and R.Tee. It is a dance track described as a funky, clap-happy piece of hip-pop confection. The lyrics follow the singer celebrating herself in a refreshing way. "Outta My Head" is the other song on