A guinea pig is a rodent, just like mice, rats and hamsters. Guinea pigs are social, and if you keep two or more females together, they'll become great friends. And if you keep males and females together, have your veterinarian neuter the males and spay the females so they can't have babies. If you're patient, some guinea pigs can be trained to use a litter box. The guinea pig is more formally known as a cavy.
Wild cavies live in family groups in the mountains and grasslands of South America.