A river is a body of flowing water in a natural channel. Rivers are extremely varied. Some rivers are very long for example, the Amazon river in South America flows through nine countries.
Some rivers, such as the Zambezi River in Africa, flow through steep gradient along the paths and fall from great heights to form beautiful waterfalls. Other rivers have become very important sites for settlements and major cities have developed along them. Examples are London on River Thames, Bangkok on the Chao Phraya River and New Orleans on the Mississippi River.