All cats are members of the Felidae family. Interestingly enough, the cat family split from the other mammals at least 40,000,000 years ago, making them one of the oldest mammalian families. This is the reason they are so distinct and different from many other mammalian families, developing and evolving on their own branch for so long.
All cats share certain characteristics that are unique to the cat family. They are pure carnivores. They need a high level of protein in their diets - around 30% - and lack the digestive equipment to do well on a diet of grains, fruits or vegetables. In fact, if you were to design a creature to live from hunting mammals you would have trouble doing better than the design of the cat.
The have powerful jaws, long, sharp teeth, and claws that draw back into their paws when not in use. Cats hear extremely well. Their eyes are adapted for vision in dim light for hunting just before dawn and just after dusk, the prime hunting periods.