Herpetology is the branch of zoology concerned with the study of reptiles and amphibians, including their classification, ecology, behavior, physiology, anatomy, and paleontology. The etymology of the term is the Greek word herpeton which means "to creep".
Herpetology deals with what are called the cold-blooded tetrapods, that is, those land vertebrates which are ectothermic (deriving their body temperature from their environment) rather than endothermic (deriving their body heat from an independent, internal source). This distinction applies to most (though not quite all) living tetrapods, but may break down somewhat in regard to extinct reptilian creatures such as dinosaurs, about whose body metabolism we know frustratingly little. (See the article on Bob Bakker for more information about the warm-blooded dinosaur theory.)
The two classes dealt with in herpetology, reptiles and amphibians, share "cold-bloodedness" but otherwise have surprisingly little else in common. Typically, amphibians have a permeable skin that assists in the exchange of gases and respiration, have a two-chambered heart like fish, and are often bound to water for at least some part of their life, if only the laying of eggs or birth of young. Their skins have many glands and are often toxic. Reptiles, by contrast, have a dry watertight skin, usually protected by scales, that normally has few if any glands. The reptilian heart is a three-chambered one (four-chambered in the case of crocodilians), and living reptilians usually if not always lay eggs or give birth on land, even marine turtles which only come ashore for this purpose. Again, extinct creatures may have exhibited some differences.
Apart from being an intrinsically interesting area of study in its own right, herpetology offers benefits to humanity in the study of the role of amphibians and reptiles in global ecology, in particular in the role of amphibians as long-range ecological warning devices (their decline worldwide is the subject of much study) and the use of the toxins of some amphibians and venoms of some snakes in human medicine.