A relaxed dog will have a loose, floppy body posture. Their tail will be wagging loosely and their ears will be perked up.
A submissive dog will have a low body posture, with their tail tucked between their legs and their ears flattened back against their head.
An aroused dog will have a stiff body posture, with their tail held high and their ears perked up. They may also be panting or drooling.
An aggressive dog may have a stiff body posture, with their tail held high and their ears perked up. They may also be growling, barking, or snapping.
Tail wagging is often a sign of happiness, but it can also be a sign of other emotions, such as excitement or nervousness. Pay attention to the rest of the dog's body language to get a better understanding of what they are trying to communicate.
Yawning can be a sign of tiredness, boredom, or stress. If your dog is yawning frequently, it is important to provide them with plenty of opportunities to exercise and play.
Eye contact can be a sign of dominance or aggression. If your dog is avoiding eye contact, it may be a sign that they are feeling submissive or fearful.