The members belonging to the family Felidae are called felids. Felids have a worldwide distribution except in few places. They live in a diverse range of habitats. Felids are broadly classified into two groups: big cats (cheetah, tiger, lion, leopard, clouded leopard, snow leopard and jaguar) and small cats (bobcats, wild cats, lynx etc. in the genus Felis). The basic difference between the big and the small cats is that some big cats can roar, while small cats can purr but can not roar. The big cats have a round pupil in their eyes, whereas, it is generally vertical in many small cats. The size of felids ranges from a small black footed cat weighing 1-2 kg to Siberian tiger that weighs more than 350 kg. Short and rounded heads with flat face, large and well developed brains, and short legs are the general features of felids. With the exception of Pall as' s cat and lynx, all the felids have 30 teeth (I: 3/3; C: 1/1; PM: 3/2; M: 1/1). They are generally nocturnal though some animals may prowl by day. The majority species are solitary, extremely secretive and are not easily accessible. Felids when surrounded with their young become dangerous. Some members are good swimmers. Felids have always been fascinated by human beings for their elegant looks. Many members are very popular zoo exhibits.