An ecosystem consists of a community of living organisms interacting with each other and their non-living environment. Ecosystems are important because they provide benefits to the environment and people. There are two main types of ecosystems - terrestrial ecosystems found on land, and aquatic ecosystems found in bodies of water. Terrestrial ecosystems include forests, grasslands, deserts and mountains, each with their own characteristic flora and fauna. Aquatic ecosystems include marine ecosystems in the oceans and freshwater ecosystems in ponds, lakes, rivers and wetlands.