wagging

Wagging refers to the rapid side-to-side or up-and-down movement of a body part, most often the tail. It is observed in many mammals, birds, and other animals, with dogs being the most familiar example. The motion is produced by the muscles at the base of the tail and is coordinated by the nervous system.

In dogs, tail wagging functions as a form of social communication. The speed, amplitude, and direction of the wag, along with the tail's height and stiffness, can signal emotional state and intent to others. Broad, fast wags with the tail held high commonly accompany greeting, excitement, or friendly intent, while slow or tentative wags can indicate uncertainty. A tucked tail may accompany fear or submission. A stiff, forceful wag can precede or accompany alertness or arousal. Because context matters, wagging does not always indicate happiness; misinterpretations can occur in unfamiliar situations or breeds.

Other animals display wagging or related tail movements, though not all use the same pattern. In horses, tails are more often swished to repel insects, while cats may flick or lash their tails to reflect irritation or focus. Humans may imitate wagging in gestures or performance, and the concept is used in animation and robotics to convey lifelike behavior.