Hussar refers to a number of types of light cavalry which originated in Hungary.
A type of irregular light horsemen was already well established by the 15th century in medieval Hungary. Etymologists are divided over the derivation of the word 'hussar'. Many scholars believe the word originated in Serbian as 'Husar', derived from the Latin root 'cursus' meaning 'raid'.
The hussars reportedly originated in bands of mostly Serbian warriors crossing into southern Hungary after the Turkish invasion of Serbia at the end of the 14th century. Initially they fought in small bands, but were reorganised into larger, trained, formations.
The first Hussar regiments were the light cavalry of the Black Army of Hungary, which took part in the war against the Ottoman Empire in 1485 and proved successful against the Turkish Spahis as well as against Bohemians and Poles. The Habsburg emperors hired Hungarian hussars as mercenaries to serve against the Ottoman Empire and on various battlefields throughout Europe.
The "father" of the US cavalry in 1777 was a Hungarian hussar named Kovács Mihály - Michael de Kovats.
The hussars played a prominent role as cavalry in the Napoleonic Wars (1796–1815). As light cavalrymen mounted on fast horses, they would be used to fight skirmish battles and for scouting. Most of the great European powers raised hussar regiments. The armies of France, Austria, Prussia, and Russia had included hussar regiments since the mid-18th century. In the case of Britain four light dragoon regiments were converted to hussars in 1806-1807.
On the eve of World War I there were still hussar regiments in the British (including Canadian), French, Spanish, German, Russian, Dutch, Danish, Swedish, Romanian and Austro-Hungarian armies. In most respects they had now become regular light cavalry, recruited solely from their own countries and trained and equipped along the same lines as other classes of cavalry.
After horse cavalry became obsolete, hussar units were generally converted to armoured units, though retaining their traditional titles. Hussar regiments still exist today, in the British Army (although amalgamations have reduced their number to two only), the French Army, the Swedish Army (Livregementets husarer, the Life Regiment Hussars), the Dutch Army and the Canadian Forces, usually as tank forces or light mechanised infantry.