What is the outermost layer of human skin called?

The epidermis is the outermost layer of human skin.

It forms a protective barrier between the body and the external environment. The epidermis is made mainly of keratinocytes, cells that produce keratin, a tough protein that helps resist abrasion and reduces water loss. Unlike the dermis beneath it, the epidermis contains no blood vessels and receives nutrients by diffusion from deeper tissues.

The epidermis is organized into layers, or strata, with the stratum basale at its deepest edge and the stratum corneum at the surface. New cells form near the base and gradually move outward as they mature. Melanocytes in the epidermis produce melanin, which contributes to skin color and helps protect cell nuclei from ultraviolet radiation.