According to Sushruta:- The development of Twacha follows after the Fertilization of Shukra and Shonita. The development of Twacha is caused by Tridosha particularly Pitta. The formation and further development of Twacha is similar to the formation of Santanika (cream) when milk is boiled. Just as the Santanika forms layers and gradually increase in thickness; similarly all layers are formed in the developmental stages of the embryo and join together to become the skin on the outer surface of fully developed child.

Twacha (Skin:-) covers the whole body it protects the body from various physical and chemical stimuli present in the environment.