Artificial waterways, such as canals, are man-made channels of water that are used for transportation, irrigation, and other purposes. Canals are typically constructed by digging a trench, building walls to contain the water, and then filling it with water. Canals are often used to connect two bodies of water, such as rivers or lakes, or to provide a navigable route between two points. Canals have been used since ancient times, and are still in use today in many parts of the world.