Animal diversity refers to the variety of animal species found on Earth, encompassing millions of different organisms. This diversity is categorized into various groups, including mammals, birds, reptiles, amphibians, fish, and invertebrates. Each group exhibits unique characteristics and adaptations that allow them to thrive in different environments, from oceans to forests. The study of animal diversity helps scientists understand ecosystems and the roles each species plays within them. Conservation efforts aim to protect endangered species and their habitats, ensuring that the rich tapestry of life continues to flourish. Key concepts in this field include biodiversity, ecosystems, and conservation.