NCT 127 is the first fixed and second overall sub-unit of the South Korean boy band NCT, formed and managed by SM Entertainment. They debuted on July 7, 2016 with the single "Firetruck" and an original lineup of seven members: Taeil, Taeyong, Yuta, Jaehyun, Winwin, Mark, and Haechan.
The third sub-unit of the NCT Universe. They were intended to be the teenaged unit of NCT before shifting away from their youthful image and re-branding in 2020, once all members became legal adults in South Korea. The sub-unit debuted on August 25, 2016 with the single "Chewing Gum" and a lineup of seven members—Mark, Renjun, Jeno, Haechan, Jaemin, Chenle, and Jisung—whose average age was 15.6 years old
The fourth sub-unit and China-based unit of the NCT. The group debuted on January 17, 2019 with their digital extended play (EP) The Vision. Their lineup consists of seven members: Kun, Ten, Winwin, Lucas, Xiaojun, Hendery, and Yangyang.
In january 2018, SM Entertainment unveiled NCT 2018, a project involving all 18 members of NCT at the time. Featuring all prior members and introduced new members Kun, Lucas, and Jungwoo. In February, NCT released a series of online documentary videos titled NCTmentary as part of the NCT 2018 project. NCT released their first full-length album, NCT 2018 Empathy, on March 14
In September 2020, NCT announced a reunion for a second group project, NCT 2020, in October 2020.The first part of their second album, NCT 2020 Resonance Pt. 1, was released on October 12. The record featured all four existing units and two new members, Shotaro and Sungchan, who are set to debut with a future NCT unit.
On November 13 2021, NCT announced their third group project, NCT 2021, with their third studio album Universe which was released on December 14. The album includes 13 songs, including the lead singles "Universe (Let's Play Ball)", pre-released on December 10, and "Beautiful"