Epithelial tissue is classified into different types based on cell shape and arrangement. The main shapes include squamous (flat), cuboidal (cube-like), and columnar (tall and column-like). These shapes can be arranged in single layers, known as simple epithelium, or in multiple layers, called stratified epithelium. Each type of epithelial tissue serves specific functions. For example, simple squamous epithelium facilitates diffusion and filtration, while stratified squamous epithelium provides protection against abrasion. Other types, like ciliated columnar epithelium, help in moving substances across surfaces, showcasing the diverse roles of epithelial tissues in the body.