Why does a cat's tail curl inward and what does it indicate about their mood or behavior?

A cat's tail curls inward as a sign of contentment or relaxation. When a cat is feeling happy and comfortable, their tail may curl inward as a way to show their positive mood. On the other hand, if a cat's tail is puffed up and bristled, it may indicate that they are feeling scared or threatened. Paying attention to a cat's tail position can help you understand their mood and behavior better.