to Twitter Share to Facebook Girls' Generation-TTS  (also known as  Girls' Generation-TaeTiSeo  and  TaeTiSeo ) is the first official sub-group of South Korean girl group  Girls' Generation , formed by  S.M. Entertainment  in 2012. The sub-group is composed of three Girls' Generation members, Taeyeon  (leader),  Tiffany , and  Seohyun . Watch  SNSD