Which layer of skin is primarily treated by the practitioner in esthetics?

The epidermis is the outermost layer of the skin and is the primary focus of esthetic treatments. This layer consists of living and dead skin cells, with the topmost part referred to as the stratum corneum or horny layer, which is made up of dead skin cells that provide a barrier to the environment. Esthetic procedures, such as facials, peels, and microdermabrasion, are designed to enhance the appearance and health of the epidermis by removing dead skin cells, stimulating cell turnover, and improving skin texture and tone.

The treatments in esthetics are targeted at this layer to address issues like dryness, aging, pigmentation, and acne. By focusing on the epidermis, estheticians can help clients achieve a fresh and rejuvenated appearance. This is why the epidermis is the correct answer, as it is the primary layer that practitioners work with during esthetic procedures.