A demesne (dɪˈmeɪn,_-ˈmiːn ) or domain was all the land retained and managed by a lord of the manor under the feudal system for his own use, occupation, or support. This distinguished it from land sub-enfeoffed by him to others as sub-tenants. In contrast, the entire territory controlled by a monarch both directly and indirectly via their tenant lords would typically be referred to as their realm. The concept originated in the Kingdom of France and found its way to foreign lands influenced by it or its fiefdoms.
In England, Wales and Northern Ireland, royal demesne is the land held by the Crown, and ancient demesne is the legal term for the land held by the king at the time of the Domesday Book in 1086.
The word derives from Old French demeine, ultimately from Latin dominus, "lord, master of a household" – demesne is a variant of domaine.
The word barton, which is historically synonymous to demesne and is an element found in many place-names, can refer to a demesne farm: it derives from Old English bere (barley) and ton (enclosure).
The system of manorial land tenure, broadly termed feudalism, was conceived in France, but was exported to areas impacted by French expansion during the Middle Ages, including the British Isles after the Norman Conquest.
In this feudal system, the demesne was all the land retained and managed by a lord of the manor for his own use and support. It was not necessarily all contiguous to the manor house. A portion of the demesne lands, called the lord's waste, served as public roads and common pasture land for the lord and his tenants. Most of the remainder of the land in the manor was sub-enfeoffed by the lord to others as sub-tenants.
Initially, the demesne lands were worked on the lord's behalf by villeins or by serfs, who had no right of tenure on it, in fulfilment of their feudal obligations, but as a money economy developed in the later Middle Ages, the serfs' corvée came to be commuted to money payments. With the advent of the early modern period, demesne lands came to be cultivated by paid labourers.