Nicker. This is a soft, gentle call horses use to greet one another. Mares nicker to their foals and mates. Horses who are very attached to their human caretakers sometimes nicker to them as well. You can also hear nickering at feeding time as you approach with their food.

Neigh. The neigh is used most often by horses who have been separated from the herd or from a very close companion. Neighs have a sense of urgency to them that seems to be saying, "hey I'm over here."

Snort. The snort, made by a rapid blowing of air from the nostrils, is most often heard when a horse is alarmed in some way. If a horse comes upon something that scares him, he may bolt, then spin around and snort at the offending object.

Squeal. This seems to be a message of controlled aggression. Strange horses often approach one another with heads up and necks arched. After a short muzzle sniffing session, one horse squeals. The other horse often reacts with an aggressive facial expression or a return squeal.