Man-made waterways, such as canals, are artificial channels of water constructed for transportation, irrigation, drainage, or other purposes. Canals are typically built to connect two bodies of water, such as rivers, lakes, or oceans, and are often used for navigation, commerce, and recreation. Canals have been used since ancient times, with some of the earliest examples dating back to the 4th century BC in Egypt. Today, canals are still widely used for transportation, irrigation, and other purposes.