Squamous epithelial cells are flat, scale-like cells that form a type of tissue known as squamous epithelium. This tissue is found lining various surfaces in the body, including the skin, lungs, and blood vessels. Their thin structure allows for efficient exchange of substances, such as gases and nutrients. These cells play a crucial role in protecting underlying tissues from damage and infection. In the skin, for example, they help form a barrier against environmental hazards. Squamous epithelial cells can be classified into different types, including simple squamous epithelium and stratified squamous epithelium, depending on their arrangement and function.