When a cat wants to express satisfaction or pleasure, it purrs. Purring of a contented cat results in a low vibrating noise. It is a kind of low, continuous rattling hum and has nothing to do with a cat’s real voice. A mother cat purrs when it wants to call her kittens for feed. At birth, the kittens cannot see, hear or smell. In the initial stages after birth, it is the purring of their mother that helps them to keep contact. Once the kittens start feeding themselves, the mother stops purring. So, we can conclude that purring began as a kind of homing device. Now the question arises — how does a cat produce the purr? The vibrations in a cat’s vocal cords cause the purring sound. When a cat takes air into its lungs, the air passes through the voice box that contains the vocal cords. If the cat then wants to express its satisfaction, it will allow the vocal cords to vibrate as the air passes in and out of the lungs while breathing. When it chooses not to purr, the air does not affect the vocal cords and thus does not produce any sound. Although there are many members of the cat family such as lion, tiger, leopard, jaguar, ocelot and lynx, whose throat structure is quite different from that of a cat and hence they cannot purr. However, they can make other kinds of sounds.