In the fields of dermatology and zootomy, the largest organ of the integumentary system is the skin. The skin is made up of epithelial tissues in a number of layers, and these tissues protect the organs and muscles which lie below. The pigmentation of the skin differs from population to population. Skin pigmentation refers to the skin color of human skin. There are different types of skin as well, and it can be of any type from oily skin to dry skin.