Cats, Felis catus L. (Carnivora: Felidae), were domesticated because of their role in rodent control around human settlements. Free-roaming cats (henceforth, referred to as "cats") can predate on a wide variety of small-to mediumsized animals and affect biodiversity. The impact of cats on biodiversity varies from country to country, region to region, and habitat to habitat. Depending on the location and context, the overall impact of cats on biodiversity can be negative, neutral, or positive. Management of cats should take into account the complex interactions that occur between cats, rodents, and the species they prey upon.