The sipahi were professional cavalrymen deployed by the Seljuk Turks and later by the Ottoman Empire. Sipahi units included the land grant–holding (timar) provincial timarli sipahi, which constituted most of the army, and the salaried regular kapikulu sipahi, or palace troops. However, the irregular light cavalry akıncı ("raiders") were not considered to be sipahi. The sipahi formed their own distinctive social classes and were rivals to the janissaries, the elite infantry corps of the sultans.

Timariot was the name given to a Sipahi cavalryman in the Ottoman army. In return for service, each timariot received a parcel of revenue called a timar, a fief, which were usually recently conquered plots of agricultural land in the countryside. Far less commonly, the sultan would grant a civil servant or member of the imperial family a timar. Also non-military timar holders were obliged to supply the imperial army with soldiers and provisions.