We all are familiar with a cat's purr - it sounds very pleasing, but are there reasons behind why do they do it? Research says that cats generally purr when they are in a good mood or content. It is a method of expressing their feelings. The purr is a soft, continuous hum and is not connected to the cat's real voice.

A purr can also be the mother cat's way of calling her kittens for feeding - in a soothing manner. At the time of birth, like all other babies of other species, the kitten's sense organs are not completely developed; the eyes are generally shut and they can neither hear nor smell. So purring becomes a method of communication between the mother and child; the kitten can feel safe and comfortable whenever it hears the purring sound. But it is also seen that once the kittens start feeding, the mother stops purring, so it acts as a type of homing device - something to tell the kittens where their mom is.

How does a cat purr? Just as we humans make sounds when air vibrates within the voice box, similarly, when the cat takes in a deep breath, and the air passes through the voice-box, containing the vocal cords. As we can choose when to speak or sing or make sounds, the cat too can decide when it wants to purr. When is a pleasant mood, it will allow the vocal cords to vibrate as the air moves through (during breathing) which causes the purring sound and in other situations, the vocal cords remain unaffected by the passing air.