Other small streams and rivers, called tributaries, flow into the river and it increases in size as it travels along. The river eventually slows down, curving around to make large bends called meanders. The river ends its journey when it flows into the sea, or a large lake. Some rivers are frozen for part of their journey. These are called glaciers.

Cities, towns and villages have grown up on or near rivers because people use the water for many purposes. People need water to drink and to grow food. They use rivers for transporting people and goods.

Some rivers are dammed to form reservoirs for drinking water, or to make electricity called hydro-electric power.

Water is constantly flowing from rivers towards the sea. The sun heats up the water and it evaporates into the air to form clouds. The clouds are blown inland to higher ground. When the clouds get cooler they condense and fall as rain. Some of the rain falls onto the land and drains back into the rivers. The water eventually finds its way back to the sea again.