During medieval times, two distinctions of cavalry had emerged: heavy and light cavalry.
Heavy cavalry referred to those soldiers who were heavily armored and used as shock troops, charging their enemies with lances. Knights often charged in close formation, similar to the shoulder to shoulder tactics of infantry charges in nineteenth century American armies. The sight of a line of heavily armored knights charging at full gallop had a profound psychological impact on the enemy.
Light cavalry carried less armour and were more of a reconnaissance force, used for scouting, screening and skirmishing.
By the 1700s, heavy cavalry still played a role as shock troops, and light cavalry were still used as reconnaissance, but a new type of unit, dragoons, regarded as a medium cavalry, had emerged. Whereas cavalry did most of their fighting on horse, dragoons rode into battle and then did most of their fighting dismounted; although, they were actually trained to fight both ways. The term "dragoon" came from the nickname for their weapon, the carbine or short musket, called "the dragon," which referred to the fire that emits out of the gun when fired, hence the term "dragon" or dragoon soldiers.