This is one of the major differences in reptiles and amphibians. Most reptiles, are considered to be tetrapods, or 4 legged animals. Though snakes are the exception to this, it is believed that the snake evolved from a reptile who had four legs. The body of a reptile works optimally when it can get the right amount of heat from its surroundings. That is why you will often see reptiles lying on a rock, basking in the sun.
Different reptiles thrive in different environments.
Some reptiles prefer cool weather and will thrive in temperatures as cold as fifty degrees, while others prefer a warm climate, having temperatures up to 104 degrees Fahrenheit. When the temperature is not conducive to a reptile, they can go into a state of hibernation and wait until the weather is right for them to be active. Even during their active times they have to vary their periods of exposure seeking the cool of shade or underground to conserve energy. A reptiles scaly skin absorbs heat from the sun and prevents animals from drying out. As a reptile grows, it sheds its outer layer of skin.