The stratum corneum consists mainly of lipids, proteins, enzymes, and water. The outer lipid membrane of the stratum corneum consists mainly of ceramides and derivatives (40%), cholesterol (25%), and free fatty acids (10-15%), with a small number of triglycerides, stearyl esters, and cholesterol sulfate. These lipids are synthesized throughout the epidermis, collected in granules and subsequently decomposed and then form the water barrier. Many factors can interfere with their synthesis path, for example, lack of essential fatty acids, enzyme inhibitors, deficient enzymes, defective enzymes, environmental factors, agents applied from the surface and the water content of the stratum corneum. The stratum corneum contains approximately 30% water, which ensures its elasticity. A healthy stratum corneum contains 10% tightly held water. Tightly held water depends on the presence of natural moisturizing factor. The natural moisturizing factor consists of amino acids and their metabolites. These metabolites are the by-products formed by the destruction of filaggrin. The natural moisturizing factor is found only inside the cells. One of the common problems related to damaged stratum corneum is dry skin. Additionally, depending on dry skin, many skin diseases such as atopic dermatitis and scaled skin can manifest. Moisturizers are agents that repair the damaged stratum corneum. Moisturizers soften the stratum corneum and make it more flexible by increasing its hydration, therefore allows a more smooth, more flexible, healthier skin.