Cats purr for a variety of reasons, not just when they are happy. Purring is a way for cats to communicate their emotions and needs, and it can signify a range of emotional states, including happiness, contentment, anxiety, stress, and even pain. Some of the reasons why cats purr include:

• To show affection/contentment: Cats may purr and rub up against their owners or cuddle up on their chest while purring to show that they feel happy in their presence.

• To express hunger: Cats may purr when its mealtime and theyre hungry, and they may combine their normal purr with an unpleasant cry or mew to get their owners attention.

• To self-soothe: Cats may purr in stressful situations to self-soothe, and they may also purr when theyre injured or in pain.

• To communicate with other cats: Cats may purr to communicate with other cats, such as to signal that they are not a threat or to solicit play.

• To communicate with humans: Cats may purr to communicate with their owners, such as to solicit attention or to indicate that they are feeling happy or content.

Overall, purring is a complex behavior that can have multiple meanings depending on the context and the individual cat. While it is often associated with happiness and contentment, it is important to pay attention to other cues, such as body language and vocalizations, to understand what a cat is trying to communicate.