Epithelial cells are specialized cells that form the protective layer of tissues in our body. They line surfaces and cavities, such as the skin, lungs, and digestive tract. These cells play a crucial role in protecting underlying structures, absorbing nutrients, and secreting important substances like mucus and hormones. There are different types of epithelial cells, each serving unique functions. For example, squamous epithelial cells are flat and help with diffusion, while cuboidal epithelial cells are cube-shaped and are involved in secretion and absorption. Together, these cells maintain the integrity of organs and contribute to overall health.