Pigmentation
Put simply, skin pigmentation describes the colour or tone of the skin. This is something controlled by melanin, a natural substance that also has had an impact on the colour of the hair and the eyes.
A skin pigmentation disorder, which can take on the form of either hyperpigmentation or hypopigmentation, is where the skin appears lighter or darker than it does on the rest of the body, with sun damage, hormonal changes, ageing and certain medications common triggers for this type of condition.
Also occurring as part of things such as acne, pigmentation disorders often become more of a possibility with age and will more readily affect those with darker skin types.