Why do animals like dogs wag their tails?

Dogs and other animals use tail wagging as a form of communication. Tail wagging can signal a variety of emotions, such as excitement, happiness, or even anxiety. A wagging tail generally indicates that the animal is engaged or feeling positive, though the speed and direction of the wag can communicate different things. For example, a slow wag might signal uncertainty, while a fast wag with a relaxed posture typically means the animal is happy and content. Tail wagging is a social signal that allows animals to communicate with each other and with humans.