Hyoyeon (효연) is a South Korean singer-songwriter, DJ, and composer under SM Entertainment. She is a member of the girl group Girls' Generation, and its second sub-unit Girls' Generation-Oh!GG.
As a DJ, she goes by the name HYO.
Hyoyeon's formal dance training began in elementary school; she learned hip hop, jazz, and Latin dance at her neighborhood's hip-hop school.
She auditioned for SM Entertainment at the age of 11 through SM's 2000 Casting System. In 2004, she, alongside Super Junior's Siwon, were sent to Beijing to study Chinese.
Before debuting with Girls' Generation, she worked with Janet Jackson and was BoA's silhouette dancer during a performance at Mnet Km Music Video Festival 2005.