What is the skin barrier and what does it do?

The skin barrier, also called the stratum corneum, is the outermost layer of skin that acts as your body's first line of defense. It prevents water loss, keeps irritants and pathogens out, and maintains skin hydration and plumpness. A healthy barrier looks smooth, feels comfortable, and does not react easily to products. When the barrier is damaged, skin becomes dry, red, sensitive, and reactive.