http://www.domesdaybook.co.uk/life.html
The system of landholding as portrayed throughout the Domesday Book was based on a rigid social hierarchy called the feudal system, imposed in England by William the Conqueror following his successful 1066 conquest.
"held" - Rather than being owned, as is the case nowadays, land was held from a member of society higher up the social tree. At the top sat King William who granted land to tenants-in-chief - usually lords or members of the Church, in return for their assistance in the Norman Conquest. Next down the ladder came under-tenants who held land from the tenants-in-chief, and so it continued with the bottom of the ladder being occupied by peasants - villagers, bordars and cottars - who earned their opportunity to hold a small amount of land by working on the land of the lordship, and slaves, who held no land.
"manor" - The basic unit of land in the Domesday Book is the manor; manors could be larger or smaller than just one village, but all consisted of land and had jurisdiction over the tenants. These were part of larger administrative subdivisions of land called hundreds (wapentakes in Danish areas of the country), which contained several manors and had their own assembly of notables and representatives from local villages.
"hide" - The value of an area of land and its resources was calculated according to size, with set values on each resource unit. In some areas, the values of the manors and their geld assessments are also connected, these are the figures in hides, virgates and carucates.
"plough" - The figure in the entries giving the actual number of ploughs is the best guide to the agricultural capacity of the manor. A plough team consisted of eight oxen and either belonged to the lord who had peasants working them for him or belonged to the peasants themselves. Some areas of Sussex and Herefordshire were highly fertile and could support at least four ploughs per square mile, while the poor land of the North and the Somerset levels could only support one plough in every two square miles or more.
"demesne" - The land retained by a lord of the manor for his own use and support, under his own management, as distinguished from land sub-enfeoffed by him to others as sub-tenants.