Biodiversity is the variety of all living things, including plants, animals, fungi, and microorganisms, and the genetic information they contain, found in different ecosystems. It is usually measured in species richness, which is the count of species in an area. Biodiversity includes the number and variety of plants, animals, and other organisms that are living in an ecosystem. An ecosystem is a group of living organisms, such as plants and animals, along with their environment, that is all connected to one another. Biodiversity is important to humans for ecological life support, as it provides a functioning ecosystem that provides oxygen, clear air and water, plant pollutions, pest control, wastewater treatment, and lots of ecosystem services. Biodiversity also holds ecological and economic significance, as it provides us with nourishment, housing, fuel, clothing, and several other resources, and extracts monetary benefits through tourism. Biodiversity has cultural value to humans as well, for spiritual or religious reasons, for instance. There are three different types of biodiversity: genetic biodiversity, species biodiversity, and ecological biodiversity.