The class Amphibia contains more than 4,500 known living species. New species are being discovered so rapidly that the number may grow to more than 5,000 during our lifetimes. However, their numbers are being rapidly decimated around the globe, largely due to the encroachment of humans on amphibian habitats and from growing human-caused environmental pollution, discussed at length in the final chapter. The authors focus our attention on the "natural history" of amphibians worldwide and emphasize their interactions with their environments over time: where they live; how they reproduce; how they have been affected by evolutionary processes; what factors will determine their destinies over time. Through the experienced eyes of the authors, who are skilled observers, we come to see and understand the place of amphibians in the natural world around us.