The Shannon diversity index (also called the Shannon–Weiner index) parametrizes the diversity of a group containing multiple distinct subgroups. It is typically used in environmental science to determine the species biodiversity of a community. The biodiversity of an ecological community can be described by using the Shannon diversity index to find the effective number of species (ENS). This is the equivalent number of uniformly populated species with the same proportional biodiversity, and the species evenness value, which shows the proximity of subgroup values in a group. Given the number of species and the number of individuals in each species, the Demonstration calculates the Shannon diversity index, ENS, and the species evenness value.