Rivers are freshwater streams that are formed thanks to rainwater, springs, ice and snow.
On our planet there are many types of rivers. Most of the rivers are born in the upper part of the mountains and go through the landscape until they reach the sea and pour their waters into it.
Some are very short, but others seem infinite because they are thousands of kilometers long and cross several countries. The longest river in the world is the Amazon.
There are rivers that carry a lot of water, rivers that carry very little, and rivers that have a large quantity in winter but remain small in the hottest months of the year.
In the rivers we find aquatic plants and animals that are completely different from those that inhabit the seas and oceans. In a river you will never find a whale, but you can come across freshwater fish such as trout and salmon, or animals such as ducks, otters or crocodiles.