Skin color is usually determined by the amount of melanin pigment secreted by melanocytes; when skin is exposed to direct sunlight, it stimulates melanocytes to secrete melanin pigment, so the skin color become darker. On the other hand, skin hyperpigmentation develops due to certain causes and circumstances. So we will highlight the most important causes of skin hyperpigmentation.

1. Freckles: they are brownish spots that affect mainly people with light skin. It develops due to prolonged exposure to direct sunlight, so it usually appears in bare areas of the body. Management of freckles usually includes topical creams as well as electrocautery if medical treatment failed.
2. Melasma: it appears in the skin in the form of dark spots; it usually affects women during pregnancy. It's noted that direct exposure to sunlight exacerbates melasma. Management usually includes topical creams as well as chemical peeling if medical treatment failed.
3. Dark areas in the armpit or in between the thigh: it develops due to contact dermatitis which increases the incidence of local fungal infection and leads to darkness of these areas. It's noted that obesity play a role in development of these cases, so it's advised to lose some weight to reduce friction between skin surfaces. Management includes hydrocortisone-containing topical creams as well as local antifungal creams and skin whitening preparations.
4. Periorbital dark circles (black aura): they develop due to physical or mental stress as well as malnutrition; also smoking and alcoholism could be responsible for black aura. Management usually includes well balanced diet rich in vitamin C and avoiding physical or mental stress.