The river is a large and long flow of water that flows continuously from upstream to downstream.
There is also a river located underground, referred to as "underground river". For example the underground river in Hang Soon Dong Cave in Vietnam, the underground river in Yucatan, the underground river in Pindul Cave (Indonesia).
In some cases, a stream simply flows into the soil before it finds another body of water. Through the river is the usual way for water hujanyang down on land to flow into the sea or a large water reservoir like a lake. The river consists of several parts, starting from the spring that flows into the creek. Some creeks will join to form the main river. The water flow usually borders the channel with the base and the cliff on the left and right. The end of the river where the river meets the sea is recognized as the river mouth.
River is one part of the hydrologic cycle. Water in rivers is generally collected from precipitation, such as rain, dew, springs, underground runoff, and in certain countries also comes from melt ice / snow. In addition to water, rivers also drain sediment and pollutants.