A heerlijkheid (a Dutch word; pl. heerlijkheden; also called heerschap) was a landed estate that served as the lowest administrative and judicial unit in rural areas in the Dutch-speaking Low Countries before 1800. It originated as a unit of lordship under the feudal system during the Middle Ages. The English equivalents are manor, seigniory, and lordship. The heerlijkheid system was the Dutch version of manorialism that prevailed in the Low Countries and was the precursor to the modern municipality system in the Netherlands and Flemish Belgium.
A typical heerlijkheid manor consisted of a village and the surrounding lands extending out for a kilometre or so. Taking 18th-century Wassenaar as an example of a large hoge heerlijkheid, it was 3,612 morgens in size and had 297 houses. Nearby Voorschoten was 1,538 morgens in size and had 201 houses. Nootdorp was an ambachtsheerlijkheid of 196 morgens and 58 houses. There were 517 heerlijkheden in the province of Holland in the 18th century. All fell into the last three categories in the list below (except for a few for which this information is unknown).
Not all heerlijkheden were the same. They differed in size and composition. Also, a heerlijkheid should not be confused with a larger territory like a county (graafschap) or viscounty (burggraafschap), nor with administrative regions on par with an English shire, Dutch gouw, German Gau, or Roman or Carolingian pagus. A Flemish castellany (kasselrij or burggraafschap) was larger and different from a heerlijkheid, but they were similar in some ways.