"I" is the debut single by South Korean singer Kim Tae-yeon (better known by her mononym Taeyeon) featuring Verbal Jint, taken from Taeyeon's debut EP of the same name. The song lyrics was written by Taeyeon herself, Mafly, and Verbal Jint, while the music was composed and arranged by Myah Marie Langston, Bennett Armstrong, Justin T. Armstrong, Cosmopolitan Douglas, David Quinones, Jon Asher, and Ryan S. Jhun. It was released digitally on October 7, 2015, in conjunction with the release of the EP, and was released on Korean Broadcasting System's "K-Pop Connection" radio on October 9. Upon its release, "I" received generally favorable reviews from music critics, who praised its musical styles and Taeyeon's vocals. The single peaked atop the South Korean Gaon Digital Chart and has since sold over 2.5 million digital copies as of October 2018. To promote the song and the EP, Taeyeon made several appearances on music programs including Inkigayo, Music Bank, and M Countdown. Background and release South Korean singer Kim Tae-yeon (better known by her mononym Taeyeon) is a member and the leader of popular girl group Girls' Generation. She has been widely recognized as a talented vocalist, yet had never ventured to record her official solo album until 2015. Taeyeon's vocal abilities are showcased on tracks she recorded for Korean films and televisions, including "If" (Hong Gil Dong, 2008), "I Love You" (Athena: Goddess of War, 2010), and "Closer" (To the Beautiful You, 2012). In April 2015, Taeyeon is featured on labelmate Amber's song "Shake That Brass" for her debut extended play Beautiful, which generated much attention from the public. On September 10, 2015, SM Entertainment revealed that Taeyeon was working on her then-upcoming debut solo album without ensuring the exact release date. On October 7, Taeyeon's debut extended play I was officially released by S.M. Entertainment. The EP received generally favorable reviews from music critics and was a commercial success in South Korea, peaking at number two on the Gaon Album Chart. The title track, "I", was released digitally in conjunction with the release of the EP as its lead single. The song was sent to Korean Broadcasting System's "K-Pop Connection" radio on October 9. Composition "I" is a pop rock song that was compared to Taylor Swift's Red album opening track "State of Grace" by Jeff Benjamin from Billboard. The lyrics of the song were written from an autobiographical narrative perspective.