It’s important to understand that every horse is different so the more time you spend with a horse, the better you can interpret their behavior. Still it’s good to make note of some basic horse body language.
Horses may try to reciprocate being groomed by someone they like by nibbling his or her shoulder, hands etc.
Angry or frustrated horses will often swish their tails. Tail swishing is a sign of agitation and it warns other horses to keep their distance. However, tail swishing is also a natural reaction to alleviating themselves of the little pests so you may see them do this if lots of insects are present.
Similar to dogs, horses can dangle their tail between their back legs as a sign of fear.
Stamping feet (lightly)
This may also show a horse is uncomfortable, agitated or simply excited and eager to move around. Heavy stamping is usually a sign of anger and/or fear.
A sign of playfulness, often with ears back and squeals. Young horses will play this way in the field. Bucking can also indicate fear and uncertainty, especially evident when a young horse is first being broken in; after all, it’s a way to get that unfamiliar heavy weight off their back! A kinked tail is often perceived prior to a buck.
Rearing up is another dual sided behavior. It can signal playfulness in foals in the field but if it is an angry stallion in fight mode, it can be a sign of fear when it cannot escape the situation.