Fauna is traditionally referred to as a non-domesticated animal species, but has come to include all organisms that grow or live in the wild in a wilderness area. Wildlife is present in all ecosystems. More developed urban areas, including deserts, forests, tropical rainforests, plains, grasslands and other areas, all have distinct forms of wildlife. Despite the fact that animals are not affected by human factors, most scientists agree that most wildlife is affected by human activities.

Historically, humans have tended to separate civilization from wildlife in many ways, including the legal, social and moral senses. However, some animals have adapted to suburban environments. These include animals such as domestic cats, dogs, mice and gerbils. Certain religions declare that certain animals are sacred, and that in modern times, the natural environment has been promoted by activists against the wildlife of human good or entertainment.