While they are not the first type of animal that comes to mind when most people think of a pet they are a more common choice than you might think. More than 2 1/2 million households in the US alone keep at least one reptile as a pet and the average is closer to two. The most popular choice is turtles that slightly outnumber all the snakes and lizards kept as pets combined.
The reptiles commonly kept as pets can be categorized as lizards, snakes or turtles. There is another less common and almost always regulated group, the Crocodilians, which include crocodiles, gharials, caimans and alligators. Reptiles in general require a solid sided enclosure that makes it easy to control temperature and humidity and prevent escape. Aquatic species like some of the turtles also require strong water filtration to help keep down odor and prevent skin diseases caused by foul water.
Reptiles can also be classified by diet with some being meat eating carnivores like all the snakes, monitors and Tegus. Others like the day and leopard geckoes, anoles and chameleons are insectivores or insect eaters. Then there are the plant eating herbivores including the popular green iguana and tortoises. Still others like most aquatic and semi-aquatic turtles are omnivores who eat both plant and animal materials.
Certain reptiles especially herbivorous lizards and all of the turtles require specialized ultraviolet B (UVB) lighting to synthesize vitamin D3 to avoid MDB (metabolic bone disease) which can cause deformities and eventually death. A vitamin and mineral supplement should also be used to enrich the limited variety of the typical captive diet.
Reptile care varies considerably by the type of reptile, its age and being cold blooded, by the temperature as it influences their metabolism. Overall though snakes tend to require the least care with less frequent feeding than lizards and turtles of comparable weight. Of course more food in means more waste out.
In general daily maintenance consist of removing any feces or uneaten food and cleaning and sanitizing any food or water dishes used. The enclosure should be thoroughly cleaned and disinfected weekly including changing any disposable bedding.
While there are a lot of similarities in the care of all reptiles they are a diverse group. This means that any species have very particular care requirements that need to be met in a captive environment so researching the type that interest you before making a choice is important.