An amphibian is a cold-blooded vertebrate animal that typically lives a "double life," spending part of its life in water and part on land. The term "amphibian" comes from the Greek words amphi meaning "both kinds" and bios meaning "life," reflecting this dual lifestyle

. Key characteristics of amphibians include:

• They are ectothermic (cold-blooded) animals with backbones

• Amphibians usually have four limbs, though some, like caecilians, are limbless

• Their skin is soft, moist, and usually lacks scales, which allows them to absorb water and oxygen through it

• They begin life as aquatic larvae with gills (commonly called tadpoles in frogs and toads) and undergo metamorphosis to become air-breathing adults with lungs

• Amphibians need access to water or moist environments for breeding because they lay jelly-covered eggs in water, and their larvae are aquatic

• The main groups of living amphibians are frogs and toads (order Anura), salamanders and newts (order Caudata), and caecilians (order Gymnophiona)

Amphibians are important ecological indicators due to their permeable skin and complex life cycles, but many species face threats from environmental changes

. In summary, amphibians are vertebrates adapted to live both in water and on land, with a life cycle that typically includes an aquatic larval stage and a terrestrial adult stage