Is a toad a frog? That question sounds simple, but the answer starts with the names themselves, and it holds a surprise. Technically, a toad is a kind of frog. Scientists do not draw a firm line between the two: there is no scientific distinction between the names, although most frogs and toads are usually called one or the other. The animals called true toads belong to a family of frogs called Bufonidae. People still notice a difference when they look closely at the skin. A toad's skin is bumpy, a bit like warts, while a frog's skin is usually smooth and slimy.

Skin matters for another reason, because frogs breathe with lungs and also through their moist skin. Frogs take in water by absorbing it through their skin instead of drinking it. A frog's skin has to stay moist, which is why most frogs live in or near water. A toad's thicker skin loses moisture more slowly, so toads can live farther from water than most frogs. Frogs also shed their skin about once a week. The frog twists, bends and stretches a lot to loosen the old skin, then pulls the skin over its head like a sweater and usually eats it.

A toad's skin has glands that make a poison, and this poison helps protect the toad from predators. Toads have large glands behind the eyes, which are called parotoid glands, and these glands make the poison. The poison is called bufotoxin, and it can kill small animals and cause allergic reactions in people. Because the poison can harm people, the plain advice is that it is best not to handle a toad, and nobody should lick or eat one. You may have heard that touching a toad gives you warts, but in fact, touching a toad does not give you warts.

Frogs need good eyesight to catch fast insects. Their large eyes see a wide range of colors and see well in dim light, and bulging eyes let a frog see in all directions without moving its head. Then comes the tongue. In a study of how frogs catch insects, a frog's tongue captured an insect in under 0.07 seconds, five times faster than a human eye blink. A frog cannot see while its tongue is striking, so it can only make a catch by taking careful aim in advance. A frog's saliva is viscoelastic, which means it has properties of both a fluid and a solid.

Male frogs and toads call by breathing in air with their lungs and then bouncing the air between their vocal sacs and their lungs. Frogs make their calls with the help of one or two pouches of skin called vocal sacs, which work like echo chambers to amplify the sound of the call. Male bullfrogs croak to attract mates and to claim their territory. The ears of a frog are called tympanums, and they look like flat, round patches of skin behind or next to the eyes. In male bullfrogs, the tympanum, the round circle on the side of the head near the eye, is much larger than the eye.

As of November 2026, the goliath frog is the largest frog on Earth. Goliath frogs are from 17 to 32 centimeters long and weigh from 600 to 3,250 grams, and they live only in coastal Equatorial Guinea and Cameroon in West Africa. At the small end, the smallest frog species is the Brazilian flea toad, Brachycephalus pulex, as of November 2026. It had the smallest total length recorded for a frog, 7.1 millimeters. Before the Brazilian flea toad, Paedophryne amauensis, a forest-dwelling frog from Papua New Guinea, held the title of smallest frog. Cane toads are the largest toads and grow up to 9 inches (23 centimeters) long.

Poison frogs live in rainforests in Central and South America, and poison dart frogs have bright colors that warn predators they are poisonous. In the wild, poison dart frogs have poison in their skin, which makes them too toxic to touch. Names can also mislead, as the horny toad shows. You may have heard of horny toads, but in fact, animals called horny toads are not toads at all; they are lizards. The Surinam toad shows the same problem from the other side, because it is a kind of frog that lives in water, and its rough skin earned it the name toad.

Frogs and toads eat so many insects that they help keep a large part of the world's insect numbers down. As of November 2026, most scientists agree that there is a worldwide decline in frog numbers, and habitat loss and invasive species are among the biggest threats to frogs and toads. A fungus disease called chytrid is causing severe declines in many frog populations, and bullfrogs that people have introduced may be driving native frogs to extinction in some areas. Amphibians react strongly to changes in their surroundings, so scientists use them as signs of how healthy a place is.

Wood frogs spend the winter frozen and thaw out when the weather warms. You may have heard that a frozen frog is dead. In fact, a frozen wood frog thaws from the inside outward. At the start of the freeze, a wood frog's liver makes large amounts of glucose that flush into every cell in its body. Wood frogs and spring peepers can freeze completely in winter, so they can start breeding much earlier than other amphibians. As of November 2026, wood frogs are the only frogs that live north of the Arctic Circle. Scientists do not yet understand what starts a wood frog's heart again after it has been frozen for the winter.

Words to know

• viscoelastic: fluid and solid
• parotoid: poison glands
• bufotoxin: toad poison
• tympanum: frog ear