Which layer of skin is referred to as the outer layer?

The epidermis is the outermost layer of the skin, serving as the first line of defense against environmental factors such as pathogens, UV radiation, and dehydration. This layer is composed primarily of keratinocytes, which produce keratin, a protein that helps to waterproof and protect the skin. Within the epidermis, there are several sub-layers, including the stratum corneum, which is the outermost sub-layer of the epidermis itself, consisting of dead skin cells that continuously shed and are replaced.

Understanding the structure and function of the epidermis is essential for anyone in the cosmetology field, as it relates to skin care and the application of various products. For example, knowledge of how the epidermis functions can inform techniques for exfoliation and hydration in skincare regimens.