Stratified squamous epithelium is a type of tissue composed of multiple layers of flat cells. This structure provides protection against physical and chemical damage, making it essential in areas of the body that experience friction, such as the skin, mouth, and esophagus. The outermost layer is made up of dead cells that are continuously shed and replaced. There are two main types of stratified squamous epithelium: keratinized and non-keratinized. Keratinized stratified squamous epithelium, found in the skin, contains a protein called keratin that adds strength and waterproofing. Non-keratinized stratified squamous epithelium, found in moist areas like the mouth and vagina, remains flexible and moist to facilitate functions like absorption and secretion.