The term "biodiversity" is a contraction of "biological diversity," and it refers to all organisms, species, and populations, as well as their genetic variety and complex assemblages of communities and ecosystems. It also refers to the interconnectedness of genes, species, and ecosystems, as well as the interactions between them and the environment. Genetic, species, and ecosystem diversity are usually considered at three levels of biodiversity. Biodiversity refers to the diversity of life on the planet. Each of these species and organisms work together in ecosystems to preserve balance and support life, much like an intricate web.