• Streams are bodies of water that flow into riversstream image by Marek Kosmal from Fotolia.com
  
  Water bodies are areas of water, both salt and fresh, large and small, which are distinct from one another in various ways. The largest water bodies are oceans, while the smallest are brooks or streams. Smaller accumulations of water, such as puddles or swimming pools are not usually referred to as bodies of water in the geographical sense.
  
  

Ocean

• Oceans are large water bodies, made up of salt water. The Pacific Ocean is the largest ocean on earth, covering one-third of the earth's surface. The Pacific Ocean is followed by the Atlantic Ocean and the Indian Ocean in size. Oceans are important for providing food, through the many fish species that populate the oceans, for air quality and for transport via ships.
  
  

Sea

• Seas are smaller bodies of water than oceans, but still large water bodies, partly enclosed by a land mass and connected to an ocean. The largest of the earth's seas is the South China Sea, which holds hundreds of islands in its waters. The Caribbean Sea, Mediterranean Sea and the Bering Sea are some of the world's largest seas. Like oceans, seas are a source of food, and are also usually used extensively as transport lanes for ships.
  
  

Lake

• A lake is a body of water completely encapsulated by land. When a lake is very large, it is sometimes called a sea, despite not being connected to an ocean, such as the Caspian Sea in central Asia. The Caspian Sea is the World's largest lake, followed by Lake Superior in the US, Lake Victoria in Africa and Lake Aral in Russia . Lakes can be either salt or freshwater.
  
  

River

• Rivers are large flowing water bodies that typically end in an ocean or sea. Rivers are freshwater bodies of water that usually originate in mountains or areas of high elevations, and are added to by smaller bodies of water such as creeks or streams, as well as by rainfall. Rivers are historically very important for trade and transportation, and many settlements were built alongside rivers for these reasons. Rivers also provide a source of energy generation. The world's longest river is the Nile in Egypt, followed by the Amazon River in South America, and China's Yangtze and Yellow Rivers.
  
  

Glaciers

• Glaciers are frozen rivers, which move very slowly. According to the National Snow and Ice Data Center, glaciers store around 75 percent of the world's freshwater, which means if they melt, sea levels would rise by up to 230 feet. Glaciers are ancient bodies of water, with some, such as the Arctic Ice Sheet being over 40 million years old.