A river is a natural stream, usually freshwater, flowing towards an ocean, sea, lake or another river. A river often flows into the ground and becomes dry at the end of its course without reaching another body of water. Small rivers can be named like as creek, brook, rivulet, and rill. There are no official definitions for the river.

Though in some countries or communities a flowing is named by its size. Many names for small rivers are specific to geographic location. For example, a “run” is a stream in some parts of the United States, a “burn” is a stream in Scotland and northeast England, a “beck” is a stream in northern England. Sometimes a river is defined as being larger than a creek, but not always because the language is very vague.

Rivers are part of the hydrological cycle. In general water collects in a river from precipitation through a drainage basin from run off and other sources such as groundwater recharge, springs, and the release of stored water in natural ice and snowpacks.

There is the main classification of river:

  • Youthful river: A river with a steep that has very few. Its channels are deeper rather than wider. For example, the Brazos, Trinityand Ebro
  • Mature river: A river is less steep than youthful rivers and flow’s more slowly. A mature river is fed by many tributaries. Its channels are wider rather than deeper. For example, the Mississippi,  Danube, Ohio, Thames
  • Old river: A river with a low gradient and low erosive energy. For example, the Yellow, lower Ganges, Tigris, Euphrates, Indusand lower Nile
  • Rejuvenated river: A river with a gradient that is raised by tectonic For example, the Rio Grandeand Colorado River.