The epidermis layer is one of three integrated layers of the skin. The dermis and subcutis are the other two. The thickness of the epidermis and the dermis varies over different parts of the body. It is thickest on the palms of the hands and feet, where friction is needed for gripping, and it is thinnest on the eyelids, which must be light and flexible. The epidermis also grows into fingernails, toenails and hair.