Skin pigmentation disorders affect the skin color. Some pigmentation disorders only affect particular patches of skin, whereas others affect the entire body. Too much melanin makes the skin dark whereas too little melanin, makes the skin lighter. Addison's disease, Pregnancy, and sun exposure can all make the skin dark. Vitiligo, on the other hand causes patches of the skin to turn light. Albinism is a hereditary condition that affects skin colour. A person with albinism may lack skin colour together, have lighter than normal skin colour, or might have patchy skin missing colour in certain places.