A posad was a settlement

Town

A town is a human settlement larger than a village but smaller than a city. The size a settlement must be in order to be called a "town" varies considerably in different parts of the world, so that, for example, many American "small towns" seem to British people to be no more than villages, while...

, often surrounded by rampart

Defensive wall

A defensive wall is a fortification used to protect a city or settlement from potential aggressors. In ancient to modern times, they were used to enclose settlements...

s and a moat

Moat

A moat is a deep, broad ditch, either dry or filled with water, that surrounds a castle, other building or town, historically to provide it with a preliminary line of defence. In some places moats evolved into more extensive water defences, including natural or artificial lakes, dams and sluices...

, adjoining a town or a kremlin

Kremlin

A kremlin , same root as in kremen is a major fortified central complex found in historic Russian cities. This word is often used to refer to the best-known one, the Moscow Kremlin, or metonymically to the government that is based there...

, but outside of it, or adjoining a monastery

Monastery

Monastery denotes the building, or complex of buildings, that houses a room reserved for prayer as well as the domestic quarters and workplace of monastics, whether monks or nuns, and whether living in community or alone .Monasteries may vary greatly in size – a small dwelling accommodating only...

 in the 10th to 15th centuries. Usually it was inhabited by craftsmen and merchants, known as posadskiye lyudi (posad people).

In the Russian Empire

Russian Empire

The Russian Empire was a state that existed from 1721 until the Russian Revolution of 1917. It was the successor to the Tsardom of Russia and the predecessor of the Soviet Union...

 a posad was a small semi-urban settlement.

A number of posads evolved into towns. Those by a kremlin often gave rise to local toponyms, such as Nagorny Posad (Uphill Settlement), and Kazanski Posad for the historical center of Kazan

Kazan

Kazan is the capital and largest city of the Republic of Tatarstan, Russia. With a population of 1,143,546 , it is the eighth most populous city in Russia. Kazan lies at the confluence of the Volga and Kazanka Rivers in European Russia. In April 2009, the Russian Patent Office granted Kazan the...

. Those by a monastery often gave rise to cities named after the monastery, e.g., Sergiev Posad is named after the nearby Troitse-Sergiyeva Lavra

Troitse-Sergiyeva Lavra

The Trinity Lavra of St. Sergius is the most important Russian monastery and the spiritual centre of the Russian Orthodox Church. The monastery is situated in the town of Sergiyev Posad, about 70 km to the north-east from Moscow by the road leading to Yaroslavl, and currently is home to...

. See also Pavlovsky Posad

Pavlovsky Posad

Pavlovsky Posad is a town and the administrative center of Pavlovo-Posadsky District of Moscow Oblast, Russia, located from Moscow, at the confluence of the Klyazma and the Vokhna Rivers. Population: The Moscow–Vladimir railway goes through the town....

, Mariinsky Posad

Mariinsky Posad

Mariinsky Posad is a town and the administrative center of Mariinsko-Posadsky District of the Chuvash Republic, Russia, located on the right bank of the Volga River, east of Cheboksary. Population:...

 and Gavrilov Posad

Gavrilov Posad

Gavrilov Posad is a town in Ivanovo Oblast, Russia, located on the Voymiga River at its confluence with the Irmes River, southwest of Ivanovo. Population: Gavrilov Posad was first mentioned a legal document in 1434 as Gavrilovskoye settlement...

.