Reptilia, commonly known as reptiles, is a class of cold-blooded vertebrates that includes snakes, lizards, turtles, and crocodilians. They are characterized by their scaly skin, which helps prevent water loss, and most lay eggs with leathery shells. Reptiles are found in a variety of habitats, from deserts to forests, and play essential roles in their ecosystems as both predators and prey. They have adapted to survive in diverse environments, showcasing a wide range of sizes and behaviors, making them a fascinating group of animals to study and observe.