Hedgehog is a spiny mammal of erinaceinae subfamily of Erinaceidae. Through introduction, 17 species of hedgehogs are found in Europe, Asia and parts of Africa as well as five genera in New Zealand. There are no hedgehogs native to Australia and no living species native to the Americas (extinct genus amphechinus once existed in North America). Hedgehogs have a distant ancestral relationship with SH (family so), and exercise may be the middle link. In the past 15 million years, hedgehogs have changed little. Like many of the first mammals, they have adapted to nightlife. The protection of hedgehog is similar to that of porcupine and echinopoda.

Hedgehog, which began to be used around 1450, originated from the Middle English heyghoge and heyg, hegge ("hedge"), because it often lives on the hedge and often haunts the pig's head. Other names include wild children, hedgehog and fur piglets. The collective noun of a group of hedgehogs is array.

Hedgehogs are easily recognized by prickles, which are hollow hairs hardened with keratin. Their spines are non-toxic or spineless. Unlike porcupines, they are not easily separated from the body. However, the vertebrae of juvenile animals are usually replaced by adult vertebrae. This is called "quilling.". When animals are sick or under extreme stress, the spine also falls off.

All hedgehogs have the defensive ability to stab the ball into a tight ball so that all the spikes point outward. The hedgehog's back contains two large muscles that control the position of the quilt. When the creature is rolled into a ball, the feather pen on the back protects the wrinkled face, feet and abdomen without gaps. Because the effectiveness of this strategy depends on the number of spines, some hedgehogs that have evolved to carry less weight are more likely to escape or even attack, using spines to hit the invaders. Turning these species into spikes is a must. All kinds of species are prey of different predators: Forest hedgehogs mainly prey on birds (especially owls) and ferrets, while smaller species such as long eared hedgehogs prey on foxes, wolves and mongooses.

Hedgehogs are mainly nocturnal, although some species can also move during the day. Hedgehogs spend most of the day sleeping under bushes, bushes, rocks, or, most often, in burrows dug underground, and their habits vary from species to species. Although not all, all wild hedgehogs can hibernate, depending on the temperature, the species and the abundance of food.