How will I know (who you are) (1999)
Jessica (born Jessica Sooyeon Jung; April 18, 1989 in San Francisco, California), is an American singer, songwriter, actress, and businesswoman. She is former member of the South Korean idol group, Girls' Generation. She is also the older sister of f(x)'s member Krystal Jung.

Having moved to South Korea when she was 11, Jessica trained for 7 years before being placed in Girls' Generation, and went on to debut in 2007. She has been praised for her talent on stage and exceptional vocals.