A reptile is a cold-blooded animal with scaly skin that usually lays eggs. Snakes, lizards, turtles, and crocodiles are all reptiles. Unlike mammals and birds, reptiles do not generate enough of their own body heat to stay warm, so you'll often see them basking in the sun on warm rocks to raise their temperature, or hiding in cool shade when they get too hot.

Reptiles have been around for over 300 million years. Dinosaurs were reptiles, and today's reptiles are their distant relatives. Most reptiles have tough, waterproof scales instead of fur or feathers, which helps protect them and keeps moisture inside their bodies. This adaptation lets many reptiles thrive in hot, dry places like deserts.

The word can also describe a person who acts in a sneaky, untrustworthy way, though this use is harsh and unkind. If someone calls another person reptilian, they mean cold and calculating, suggesting the false idea that reptiles don't have feelings. In reality, reptiles are fascinating creatures perfectly adapted to their environments. Many people keep reptiles like geckos, corn snakes, or turtles as pets, learning to appreciate their unique behaviors and needs.