Cats purr for a variety of reasons, and it is not always a sign of happiness or contentment. Purring is the most common sound that cats make, and it can signify a range of emotional states, including happiness, anxiety, or another emotion. Here are some of the reasons why cats purr:

• To show affection/contentment: Cats may purr and rub up against you or cuddle up on your chest while purring to communicate contentment or happiness.

• To express hunger: Cats may purr around dinnertime to get your attention and signal that they are hungry.

• To self-soothe: Cats may purr to get relief from stress or pain, especially if they are battling an infection or other injury.

• To get your attention: Cats may purr to signal that they want pets, food, or to play.

• To communicate with other cats: Cats may purr to communicate with other cats, especially when they are injured or stressed.

• To bond with their mother: Kittens can purr at only a few days old, and it is a way that they let their mothers know where they are or that they are okay. Purring also helps a kitten and mother bond, and mother cats use purring as a lullaby.

Overall, cats purr for many reasons, and it is important to consider the situation and context to understand what your cat is trying to communicate.