On & Off is a South Korean television program that airs on tvN.

Sung Si-kyung is a South Korean singer, entertainer and television host. He debuted in 2001 and has released eight studio albums in Korean and two studio albums in Japanese. He has also hosted and appeared on numerous South Korean variety television shows including 2 Days & 1 Night, Witch Hunt, Non-Summit, Duet Song Festival, Vocal War: God's Voice, Battle Trip, The Voice Of Korea 2020, On & Off.