Cats are mammals. The main characteristics of mammals include: body hair, viviparity, lactation, etc. Cats meet these characteristics:

Coat: A cat's body is covered with hair, which helps maintain body temperature and protect the body.

Viviparous: The cat is connected to the female cat through the placenta and umbilical cord, develops and gives birth inside the female cat's body.

Lactation: After the kittens are born, the mother cat will secrete milk through her mammary glands to feed them.