A community is made up of all of the populations of different species living in a specific environment. A community is only the living components of the environment. For example, all of the algae, plants, frogs, fish, and other organisms living in and around a pond make up a pond community. The most abundant organism in the community is known as the dominant member of that community.

The species living within a community interact together in numerous different ways. These interactions play an important role in shaping the size and structure of the community. Specifically, the interactions help determine what species are present in the community, and the size of each species' population. These interactions often result in evolution of the species involved and changes in the community. The interactions fall into three general categories: competition, predation and symbiosis.

When individuals of the same or different species share...