A phenomenon, which determines the level of organisms diversity living on Earth. It refers not only to the diversity of genes, but also to variety of species or ecosystems.
One of the ways to determine biodiversity is to study the abundance of selected species in a specific localization (e.g. we know that in the coral reef in northern Australia more than 500 fish species live) or determine the impact of climatic conditions on the populations (e.g. arctic tundra inhabited by fewer species than the tropical forest).