Purring is mostly an automatic reaction, and cats do it when they’re content or need to calm themselves, but cats can also choose to purr when they need something from us.
When our cats breathe in and out, and the air hits the larynx muscles in the throat, it vibrates, making the hyoid bone resonate, thus producing this low rumble we call purring.
When purring happens, the setting is usually idyllic since whenever they make this sound, they’re most likely relaxed and enjoying your company and some thorough petting.
This sound helps strengthen the bond between kittens and their mother, as they all purr together, and it lets the mother know that her babies are close by and content.