Light cavalry comprises lightly armed and lightly armoured troops mounted on horses, as opposed to heavy cavalry, where the riders (and sometimes the horses) are heavily armored. The missions of the light cavalry were primarily reconnaissance, screening, skirmishing, raiding, and most importantly, communications, and were usually armed with spears, swords, bows and later with pistols or carbines.
Light cavalry was used infrequently by the Greeks and Romans (though Roman auxiliaries were often mounted), but were popular among the armies of Central Asia and Southwest Asia. The Arabs, Hungarians, Huns, Mongols, Turks, Parthians, and Persians were all adept light cavalrymen and horse archers.
With the decline of feudalism and knighthood in Europe, light cavalry became more prominent in the armies of the continent. Many were equipped with firearms, as their predecessors had been with bows. European examples of light cavalry included stradiots, hobelars, hussars, chasseurs à cheval, cossacks, chevau-légers, uhlans and some dragoons.
Armies of the ancient Roman-Germanic wars made use of light cavalry as patrolling squads, or armed scouts, and often had them in the front lines during regional battles.
During the Punic Wars, one of Carthage's main advantages over Roman armies was its extensive use of Numidian light cavalry. Partly because of this, the Roman general Scipio Africanus recruited his own cavalry from Sicily before his invasion of Tunisia during the Second Punic War.
A variety of types of light cavalry were developed in medieval armies.
Light cavalry played a key role in mounted scouting, escorting and skirmishing during the Napoleonic era. Light horse also served a function in major set-piece battles. While lacking the sheer offensive power of heavy cavalry, light cavalry were still extremely effective against unprepared infantry and artillery. All infantry commanders were forced to respect the danger any cavalry presented to their forces, and light cavalry were effective at changing the movement of enemy forces simply through their presence. In the aftermath of battles, light cavalry were used to press a victor's advantage or to screen retreating forces from further attack.
As late as the early 1900s, most European armies still retained a nominal division of mounted troops according to the size and weight of the men, into light cavalry (reconnaissance, scouting and screening), medium cavalry (attack and defense of specific locations) and heavy cavalry (shock action on the battlefield). While colonial warfare had led to a blurring of these distinctions in the British army, tradition remained strong in the cavalry arm of some other nations. As an example, the Imperial German army maintained a marked difference between the sizes and weights of the men and horses allocated to the hussar regiments that made up its light cavalry and those of the other two categories. The early weeks of World War I saw light cavalry attempting to continue its long established function of being the "eyes and ears" of the respective main armies. However, despite some early success, the advent of trench warfare and aircraft observation quickly rendered this role obsolete, except to an extent in the Middle East in 1917, and in Eastern Europe where light cavalry mounted actions on a diminishing scale continued to occur until the revolution of 1917 took Russia out of the war.