Girls' Generation-TTS (Hangul: ����-���, also known as TTS, TaeTiSeo, or Girls' Generation-TaeTiSeo), was the sub-unit of the girl group Girls' Generation, formed by S.M. Entertainment in 2012. It was composed of three Girls' Generation members: Taeyeon, Tiffany and Seohyun, who the last two left the agency and the group in 2017. The group released their first EP entitled "Twinkle", in 2012. The second EP, "Holler", was released in 2014. Then in December 2015, a third EP entitled "Dear Santa" was released as a Christmas special.