The skin (a stratified tissue) is comprised of multiple layers ranging from the innermost hypodermis, to the outermost epidermis, in which the skin’s native microflora resides.  Due the exposed nature of this organ to external aggressions, it necessitates continuous renewal initiated by stem cells within the basal layer of the epidermis to protect homeostasis within the body.

These stem cells undergo a specialized division process, resulting in the formation of new cells, that further differentiate into keratinocytes necessary to produce keratin.  Under normal conditions these keratinocytes transform themselves into corneocytes, as they progress up through the epidermis. These corneocytes are non-viable cells with a tough outer structure (cell envelope) consist predominantly of cholesterol, fatty acids, and ceramides, contributing to the barrier function of the skin and preventing dehydration. 

This process of transformation is however continuous as corneocytes are regularly eliminated or shed from the surface and will therefore be replaced by cells from the deeper layers. This in conjunction with maintenance of skin microbiota completes the regeneration cycle preserving healthy skin function over time which is visible in the form of beauty.

When referring to skin microbiota this includes microorganisms such as bacteria, viruses and fungi, and although a large number of microbiota is present on the skin, most are usually harmless and beneficial. However, this nature of microbiota changes in disease states due to a change in composition or disruption in the balance between harmful microbiota and beneficial microbiota.