Biodiversity refers to the variety of life on Earth, including genetic, species, and ecosystem diversity. There are six kingdoms of life - Archaea, Bacteria, Protista, Fungi, Plantae, and Animalia. Species diversity is estimated between 2-100 million species globally, though only 1.4 million have been named. Genetic diversity refers to variation between individuals of the same species. Ecosystem diversity measures communities of plants and animals and their physical environment. Protecting biodiversity requires conserving ecological processes and maintaining reserves large enough to support complex species interactions.