Tail held up and wagging fast indicates excitement. An erect tail is a sign of alertness. A tail held between the legs is a sign of fear.

Relaxed ears mean that a dog is calm. Erect ears show that a dog is alert and attentive. Ears that are up and forward mean a dog is challenging or being assertive or aggressive. Ears that are laid back indicate that a dog is worried or scared.

Raised hackles indicate arousal, either because a dog is frightened or is challenging another dog. Smooth hackles show a dog is calm.

Yawning may indicate anticipation or stress. It increases heart rate and blood flow to the brain. Filling the lungs with oxygen and removing carbon dioxide. In fact, it helps a dog energize his body and gathers his wits.

Pawing is an appeasing gesture. Licking another dog's face is an invitation to play or sign of deference.

Panting means that a dog is feeling playful, excited or stressed, or he may simply be hot. A dog with mouth and lips closed is uncertain or appeasing.

Mounting or standing above another dog by putting front paws on the other dog's back means asserting dominance. It isn't just a male characteristics for females do it too. Mounting is more often related to social status than to sex.

Paw lifting is a dog's way to call your attention. It may be an invitation to play or a means to tell you something else.

Licking the lips is a sign that a dog is worried or is trying to appease a person or another dog. A relaxed mouth means a dog is calm. Lips pulled back is a challenging or warning sign, especially when combined with a snarl.

Play bowing is an invitation to play and a sign of happiness.

A relaxed tail means that a dog is calm and at peace. A tail head straight out, wagging rhythmically and slowly, means that a dog is cautious or on guard. Tail down indicates worry or uncertainty.

Direct eye contact means that a dog is feeling bold and confident. Casual eye contact means he's contented. An averted gaze means indifference. Dilated pupils indicate fear.