I.O.I — Where to Listen on the Radio

I.O.I (Korean: 아이오아이; also known as IOI or Ideal of Idol) is a South Korean girl group formed by CJ E&M through the 2016 reality show Produce 101 on Mnet. The group was composed of eleven members chosen from a pool of 101 trainees from various entertainment companies: Jeon So-mi, Kim Se-jeong, Choi Yoo-jung, Kim Chung-ha, Kim So-hye, Zhou Jieqiong, Jung Chae-yeon, Kim Do-yeon, Kang Mi-na, Lim Na-young, and Yoo Yeon-jung.

I.O.I debuted on May 4, 2016, with the extended play (EP) Chrysalis and its single "Dream Girls", which became their first top-ten single on South Korea's Circle Digital Chart. They followed it with the sub-unit single "Whatta Man" in August, which peaked at number two on the chart. The group released their second EP Miss Me? in October, which spawned their first number-one hit "Very Very Very".

I.O.I actively promoted as a whole and as a sub-unit for less than a year. Their instant success earned them the Rookie Artist of the Year title at the Golden Disc Awards and the Mnet Asian Music Awards. In January 2017, the group released their single "Downpour" and held the three-day concert Time Slip – I.O.I. They officially disbanded at the end of January and returned to their respective agencies.

In May 2026, I.O.I reunited after nine years in commemoration of their tenth debut anniversary. The group released their third EP I.O.I: Loop and its single "Suddenly", which became their second number-one hit on the Circle Digital Chart.