Cottontail rabbits are the leporid species in the genus Sylvilagus, 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 cottontails nor is it unique to the genus.

The genus is widely distributed across North America, Central America and northern and central South America, though most species are confined to some particular regions. Most species live in nests called forms, and all have altricial young. An adult female averages three litters per year, which can occur in any season; occurrence, and litter size depend on several factors including time of the year, weather, and location. The average litter size is four but can range from as few as two to as many as eight, most of whom do not go on to survive to adulthood.

Cottontail rabbits show a greater resistance to myxomatosis than European rabbits.