A river is a natural waterway that usually starts in mountains or lakes and flows continuously until it empties into another lake, a sea, or an ocean. A river's starting point is called its «source», and its ending point is its «mouth».
The «Nile» River in Africa is one of the longest rivers in the world, and ancient Egyptian civilization grew along its banks thousands of years ago because it watered the land and made it fertile for farming. Also famous are the «Tigris and Euphrates» rivers in Iraq, which made the land between them a cradle of the earliest civilizations.
Rivers are very important to humans — they supply fresh water for drinking and farming, are used to transport goods by boat, and provide a home for many fish and water birds.
