From ancient Egyptians to today’s internet users, people have always loved their cats.

In the U.S. alone, cats reign over about 45.3 million households. There are at least 45 domestic breeds, which differ widely in features such as coat color, tail length, hair texture, and temperament, according to the Cat Fancier’s Association.

The Maine Coon is the largest, with males reaching an average of 3.5 feet long. The smallest breed is the Singapura, native to Singapore, with adult females weighing as little as four pounds. One of the most unusual-looking cats is the Sphynx, a mostly hairless cat known for being robust and intelligent.

Like their big cat cousins, house cats are obligate carnivores, meaning they have to eat meat to stay healthy. Though they’ve been domesticated for thousands of years, these predators have maintained a strong hunting instinct, relying on stealth to stalk prey and attack with sharp claws and teeth. (Learn surprising things you never knew about your cat.)

As mostly nocturnal animals, cats have excellent vision and hearing, with ears that can turn like satellite dishes. Their reputation for having nine lives stems in part from their ability to navigate difficult environments, for example using their tail to balance and mostly land their lean, muscular bodies on all fours. Cushioning discs between vertebrae also give cat bodies exceptional flexibility and speed.