This document provides information about streams, rivers, and lakes. It discusses how streams begin as small bodies of water that flow over land and join together to form larger rivers. Rivers drain water from the surrounding land in a river system made up of the main river and its tributaries. Many early human settlements formed along rivers because rivers provided important resources. Lakes are bodies of water surrounded by land that were often formed by glaciers gouging out holes during the ice age that later filled with water. Some notable lakes discussed include the Great Lakes in North America and Lake Baikal in Russia.