The sound of a cat purring is one of the most endearing sounds to any feline fancier. It can make a cat’s owner’s heart melt. It’s also a sign that the animal is in a happy mood or wants something. But the answer to why cats purr has long remained a mystery.

The reason why cats purr can vary, but the most common is that it’s to let their owners know they’re happy and content. This can be done by a cat head bumping against you or rubbing against your legs while purring, and it’s often followed up with licking.

This kind of purring is called a "happy purr," and it typically occurs when cats are relaxed, eyes half closed, and tails still. They may be in a good mood because it’s their time to eat, or they just want your attention.

But sometimes cats will purr to ask for something, too. In recent years, researchers have found that some cat purrs, known as “solicitation” purrs, can be surprisingly distinct from ordinary purrs. They’re louder, more urgent, and can be difficult to distinguish from a normal purr.

While it’s possible that your cat may be trying to get your attention with this type of purr, it’s probably not the best way to communicate with them. That’s why it’s important to understand the context behind their purring.

If your cat isn’t able to purr for you, it could be because they’re feeling scared or nervous, says Fisher. This can be the case if they’re not used to being around other animals, or if they’re in a new environment. In addition, if your cat is sick, they’re likely to purr more to try and keep themselves calm.

The other common reason why your cat might purr is when they’re hungry or injured. The frequency of these vibrations can stimulate bone growth and reduce pain, according to Elizabeth von Muggenthaler, a bio-acoustician who studies animal sounds.

Kittens are often born blind and deaf, so they use the vibration of purring to locate their mother and nurse. It’s a signal for them that she’s there, but it’s also a form of communication between the kitten and her mother, so they can tell each other their needs.

Scientists don’t know the exact mechanism by which cats purr, but it seems to involve muscles in the larynx and throat. As they twitch, the muscles constrict the glottis, the part of the larynx that surrounds vocal cords. This causes air from the cat’s inhalation and exhalation to vibrate past the vibrating muscles, creating the familiar purring sound that we all know and love.

It’s also believed that the vibrations cause healing to occur within a cat’s body, reducing stress and helping them recover from injuries. The low frequency of purrs has been shown to help heal bones and wounds, build muscle, repair tendons, and decrease swelling.

Regardless of the reason why your cat is purring, it’s never a bad idea to check in with them and see how they’re feeling. This can help you to determine the best ways to support your pet’s health, so they continue to be as healthy as possible.