Animals, a diverse group of living organisms that consume other organisms for energy, have been a constant source of companionship, production, support, and sustenance for much of human history. Maintaining balance in our ecosystems, all animals are connected by the various important roles they play in making the environment function properly and it is the responsibility of humans to preserve and protect these fragile systems. The following collections of animal families provide an overview of the large range of varieties, sizes, and characteristics of mammals, birds, reptiles, fish and insects that coexist with humans on Earth. We will be continuing to expand our guides over time to cover in further detail the particular distinctions between the many forms of animal life in the world.