Wing Chun is a martial art that originated in China and has since become popular around the world. The tan sau is a basic technique in Wing Chun that involves defending against an opponent's punch by using a hand position called the tan sau. The tan sau is formed by extending the arm with the palm facing down and the fingers relaxed, as if holding a tray. To perform the tan sau, the practitioner steps forward with the front foot and raises the arm with the tan sau hand to deflect the punch. The tan sau can be used to defend against punches to the midsection or head, and can also be used to redirect the punch to set up counterattacks.