Epithelial tissues line structure surfaces of the body, and also form glands. These surfaces include the skin and the lining of the organs and vessels. Epithelial tissue is classified by the shape and number of its cells; single layer tissue is called simple epithelium while tissue with layers is called stratified epithelium. Flat tissue is squamous, cube-like tissue is cuboidal, and tall, thin tissue is columnar. Functions of epithelial tissue includes secretion, selective absorption, protection, transport, and detection of sensation. The shape of the cell determines the function. Epithelial cells can be connected by tight junctions, gap junctions, or desmosomes. The foot in this picture has skin which is epithelial tissue.