Porcupines are rodentian mammals with a coat of sharp spines, or quills, that protect against predators. The term covers two families of animals, the Old World porcupines of family Hystricidae, and the New World porcupines of family Erethizontidae. Both families belong to the infraorder Hystricognathi within the profoundly diverse order Rodentia and display superficially similar coats of quills: despite this, the two groups are distinct from each other and are not closely related to each other within the Hystricognathi.
The Old World porcupines live in southern Europe, Asia (western and southern), and most of Africa. They are large, terrestrial, and strictly nocturnal. In taxonomic terms, they form the family Hystricidae.
The New World porcupines are indigenous to North America and northern South America. They live in wooded areas and can climb trees, where some species spend their entire lives. They are less strictly nocturnal than their Old World relatives, and generally smaller. In taxonomic terms, they form the family Erethizontidae.
