A timariot (or timar holder; timarlu in Turkish) was an irregular cavalryman that served the Ottoman sultan and in return was granted a fief called a timar. The timariots had to assemble with the army when at war, and had to take care of the land entrusted to him in times of peace. When at war, the timariot had to bring his own equipment and in addition a number of armed retainers (cebelu). Food was supplied during campaign.

In this way, the Ottomans could quickly muster a large army. When the war was over the warriors returned to their lands, and in that way the sultan did not have to support them when he didn't need them. In addition, the sultan's lands were taken care of. Local peasants were subjects to the timariot. Law and order was kept, taxes were collected and bandits were brought to justice.

The system of timars was organized during the reign of Orhan I (1326-1359). The Sultan granted officers fiefs with local peasants subjected to their rule in an arrangement similar to European feudal fiefs. They were an important part of the Ottoman army, especially for being so easily supportable, and kept that status until the early 17th century. The titles and lands of the timar holders remained in use much longer than that.

When on campaign, the timariots were organized into regiments called alays that were commanded by alay beys (or beg). Larger units were the sanjak (or sançak) regiments or livas (standard, banner), commanded by sanjak beys. At the top were the province governors, the beylerbeys. A province in the 16th century could muster some thousand timariots, according to the size of the province. In 1525 the total number of timar holders were 37 818, according to the tax rolls. The number of armed retainers was estimated to 50 000. Of course, these great numbers were spread out all over the empire, and could not possibly serve in one campaign at a time.