Columnar epithelium is a type of tissue made up of tall, column-shaped cells. This epithelium is primarily found lining the digestive tract, respiratory tract, and some glands. Its structure allows for efficient absorption and secretion, making it essential for processes like digestion and mucus production. There are two main types of columnar epithelium: simple and stratified. Simple columnar epithelium consists of a single layer of cells, while stratified columnar epithelium has multiple layers. The cells often contain specialized structures, such as microvilli for increased surface area or cilia for movement, enhancing their functional capabilities.