Hi, how much do you know about animals? And how much do you know about cats? And this is a video about why cats purr? They pouring is a sign of expressing feeling. They purr some times for expressing their pleasure feeling and some time for expressing they are angry. And they produce some sounds like, mue, they make sound from the diaphragm. A scientific studies show that the low frequency cats makes helps make bone density. And cats purr make actually the same frequency. So that cats purring keep cats healthy. And also vibration can make human bones strength, specially it is useful for astronauts.