Cats purr for various reasons, and it is often associated with feelings of comfort, contentment, and relaxation. However, cats may also purr when they are in pain or distress, as a way to self-soothe. Purring can also be a form of communication, signaling to other cats or humans that they are feeling calm and happy. Additionally, some research suggests that purring may have healing properties and can help cats in reducing stress and promoting healing.