Simple columnar epithelium is a type of tissue made up of a single layer of tall, column-shaped cells. This epithelium is primarily found lining the digestive tract, such as the stomach and intestines, where it plays a crucial role in absorption and secretion. The cells often contain microvilli, which increase the surface area for better nutrient absorption. In addition to its presence in the digestive system, simple columnar epithelium can also be found in the uterus and parts of the respiratory tract. This tissue type is important for protecting underlying tissues and facilitating the movement of substances across its surface.