保持年輕及美麗的膚質是每一個人夢寐以求的，而達到此目的需有賴於人們對皮膚老化的認識，皮膚老化主要由内在老化（intrinsic aging)及外在老化（extrinsic aging)兩大因素決定。内在老因素主要被基因控制，出生時即決定；而外在老化因素主要由紫外線、生活習慣及環境污染等因素所影響。所以本篇文章將就幾種内在及外在影響皮膚膚質之因素做詳細陳述，讓讀者廣泛性了解，使讀者未來避免這些因素對自己的膚質產生負面之影響。

Maintain a beautiful, young looking skin is everybody’s dream, and knowing the lactors 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.