The Taeniidae /tɨˈnaɪ.ɨdiː/ are a family of flatworms. It is the largest family representing the order Cyclophyllidea. It includes many tapeworms of medical and veterinary importance, as Taenia solium (pork tapeworm), Taenia saginata (beef tapeworm), and Echinococcus granulosus. The Taeniidae are parasites of mammals and many are infectious to humans. Taeniidae parasites are distinguished by their terrestrial lifecycles, which include a dormant stage called a metacestode.