Cottontail rabbits are in the Sylvilagus genus, which is in the Leporidae family. They are found in the Americas. Most Sylvilagus species have stub tails with white undersides that show when they retreat, giving them their characteristic name. However, this feature is not present in all Sylvilagus, nor is it unique to the genus.

Leporidae is the family of rabbits and hares, containing over 70 species of extant mammals in all. The Latin word Leporidae means "those that resemble lepus" (hare). Together with the pikas, the Leporidae constitute the mammalian order Lagomorpha. Leporidae differ from pikas in that they have short, furry tails and elongated ears and hind legs.