Epithelial tissues are layers of cells that cover surfaces and line cavities in the body. They serve various functions, including protection, absorption, secretion, and sensation. These tissues are classified based on cell shape—such as squamous, cuboidal, and columnar—and the number of layers, which can be simple (one layer) or stratified (multiple layers). Epithelial tissues are anchored to underlying structures by a basement membrane, which provides support and helps with nutrient exchange. They are found in many areas, including the skin, lining of the digestive tract, and respiratory system, playing a crucial role in overall health and function.