Folwark is a Polish word derived from the German Vorwerk. A Folwark or Vorwerk is an agricultural estate or a separate branch operation of such an estate, historically a serfdom-based farm and agricultural enterprise (a type of latifundium), often very large. The term has changed its meaning several times throughout history and can therefore be used in various ways.

Originally, the associated agricultural estates were usually located outside fortifications or castles and directly in front of them, and were therefore often referred to as Folwark or, in German-speaking regions, Vorwerk, meaning advanced work or outwork, a kind of outlying defensive outpost. In place names and field names, the word can still be present in this meaning.

Later, the term was used for outposts of manor farms with estate operations or individual tenant farms. On larger estates with extensive land areas, there were often smaller and more remote branch operations in addition to the main operation. From around the end of the 18th century, these were also frequently referred to as Folwark or, in German-speaking regions, Vorwerk. In this sense, Folwark or Vorwerk appears as a name or part of a name for a variety of settlements, especially in the northern and eastern parts of Germany.

A term occasionally used in official documents for a Folwark or Vorwerk is "pertinentia" (accessory).

Folwarks (Polish: folwarki) were operated in the Crown of Poland from the 14th century, in the Grand Duchy of Lithuania from the 15th century and in the joint Polish–Lithuanian Commonwealth from the second half of the 16th century. Folwarks also developed in the Commonwealth-controlled Ukrainian lands. The institution survived after the 18th-century Partitions of Poland until the early-20th century.

Folwarks aimed to produce surplus produce for export. The first folwarks were created on Church- and monastery-owned lands. Later, the folwark system was adopted both by the nobility (szlachta) and by rich peasants (singular: sołtys), but the sołtys positions were eventually taken over by the szlachta.

The term folwark came into the Polish language in the 14th century from the German Vorwerk, originally the fortified advanced work of a castle and later an outlying manor house that managed a farm estate. The English translation would be "grange", the historical meaning of which is "an outlying farm with tithe barns belonging to a monastery or feudal lord".

The development of folwarks was boosted by growing demand for grain and by the profitability of its export, both to Western Europe and within the Polish–Lithuanian Commonwealth. That led to the exploitation of serfdom since landowners discovered that instead of collecting money-based rent and taxes, it was more profitable to force the peasantry to work on folwarks. Folwark-based grain export became an important part of the economy of the Polish–Lithuanian Commonwealth.^{[citation needed]}