|The most important function of the skin is to form a barrier between the organism and the environment. The skin barrier prevents excessive water loss and the entry of harmful substances from the environment. The stratum corneum barrier is composed of corneocytes and intercellular lipids, cholesterol, free fatty acids, and ceramides. Keratins and cornified envelope proteins are important for the mechanical stability of the corneocytes. The cornified envelope protein involucrin binds ceramides covalently, forming a backbone for the subsequent attachment of free ceamides. Experimental barrier disruption increases epidermal lipids and changes in epidermal differentiation. The signals for barrier recovery are cytokines and the calcium ion gradient. Herein, the mechanisms for the regulation of the barrier homeostasis are discussed.