Eyalets (Ottoman Turkish: ایالت, pronounced [ejaːˈlet], lit. 'province'), also known as beylerbeyliks or pashaliks, were the primary administrative divisions of the Ottoman Empire.

From 1453 to the beginning of the nineteenth century the Ottoman local government was loosely structured. The empire was at first divided into states called eyalets, presided over by a beylerbey (title equivalent to duke in English and Amir al Umara in Arabic) of three tails (feathers borne on a state officer's ceremonial staff). The grand vizier was responsible for nominating all the high officers of state, both in the capital and the states. Between 1861 and 1866, these eyalets were abolished, and the territory was divided for administrative purposes into vilayets (provinces).

The eyalets were subdivided into districts called livas or sanjaks, each of which was under the charge of a pasha of one tail, with the title of mira-lira, or sanjak-bey. These provinces were usually called pashaliks by Europeans. The pasha was invested with powers of absolute government within his province, being the chief of both the military and financial departments, as well as police and criminal justice.

At official functions, the order of precedence was Egypt, Baghdad, Abyssinia, Buda, Anatolia, "Mera'ish", and the Kapudan Pasha in Asia and Buda, Egypt, Abyssinia, Baghdad, and Rumelia in Europe, with the remainder arranged according to the chronological order of their conquest.

The term eyalet is sometimes translated province or governorate. Depending on the rank of the governor, they were also sometimes known as pashaliks (governed by a pasha), beylerbeyliks (governed by a bey or beylerbey), and kapudanliks (governed by a kapudan).

Pashaluk or Pashalik (Turkish: paşalık) is the abstract word derived from pasha, denoting the quality, office or jurisdiction of a pasha or the territory administered by him. In European sources, the word "pashalic" generally referred to the eyalets.

The term 'eyalet' began to be applied to the largest administrative unit of the Ottoman Empire instead of beglerbegilik from the 1590s onward, and it continued to be used until 1867.

Murad I instituted the great division of the sultanate into two beylerbeyiliks of Rumelia and Anatolia, in circa 1365. With the eastward expansion of Bayezid's realms in the 1390s, a third eyalet, Rûm Eyalet, came into existence, with Amasya its chief town. This became the seat of government of Bayezid's youngest son, Mehmed I, and was to remain a residence of princely governors until the 16th century.