Maintain a beautiful, young looking skin is everybody's dream, and knowing the factors related to skin aging is the key. Aged skin is a result of intrinsic aging and extrinsic aging. Intrinsic aging occurs as a natural consequence of aging and is genetically determined. Extrinsic aging, on the other hand, can be affected by UV exposure, lifestyle and environment. This article is to give readers an in-depth understanding about both intrinsic and extrinsic factors that may affect the process of skin aging, and a general idea of how to avoid factors that can be prevented in the future.