Why do cats purr?
The cat's purr is an indication of pleasure and it is also a means of communicating with its young. However, it has been discovered that cats purr more often when they are under stress or when unwell. For more information, visit http://www.scientificamerican.com/article.cfm?id=why-do-cats-purr.
well i am not sure but i think that is there way to communicate with other cats
Two reasons: 1) They're happy and 2) when they purr, they're healing sores and bones.(#2 has been proven by science)