Biodiversity, short for "biological diversity," refers to the variety of life on Earth. This includes the diversity within species, between species, and of ecosystems. It is a concept that captures the richness and variability of all living organisms—plants, animals, fungi, and microorganisms—as well as the ecosystems they form and the ecological processes they participate in.

Biodiversity is not uniformly distributed across the globe. Some areas, such as tropical rainforests and coral reefs, are especially rich in species and are referred to as biodiversity hotspots.