[citation needed] The effects of intrinsic ageing are caused primarily by internal factors alone.
It is sometimes referred to as chronological ageing and is an inherent degenerative process due to declining physiologic functions and capacities.
[citation needed] Extrinsic ageing of skin is a distinctive declination process caused by external factors, which include ultra-violet radiation, cigarette smoking, air pollution, among others.
Of all extrinsic causes, radiation from sunlight has the most widespread documentation of its negative effects on the skin.
Photodamage implies changes beyond those associated with ageing alone, defined as cutaneous damage caused by chronic exposure to solar radiation and is associated with emergence of neoplastic lesions.