The Amazon is a densely forested region that covers about 9 countries in South America, most of which is found in Brazil. Known as the "lung of the world", it is the largest existing tropical forest and one of the most important biodiversity reserves on the planet. The Amazon Rainforest is fundamental for the balance of the global climate and helps to control the level of greenhouse gases in the atmosphere. It is also an important source of natural resources, including wood, minerals, and oil.