Latin, feudum.

Most of the text for each Domesday county consists of a sequence of fiefs, a fief being the conventional term for the manors held directly from the Crown by a single landowner in a single county in 1086. Traditionally, such landowners are known as tenants-in-chief; they were normally the wealthiest and most powerful landowners in the county, and often in the country as well. Most counties also contained a collective fief in which the manors of the minor tenants-in-chief were gathered together. These minor landowners are usually described as royal thanes or servants. At a later date, they would be known as royal sergeants.

The fiefs of tenants-in-chief provide the main structure for landholding within each county in 1086. Landholding structures appropriate to 1066 are not, therefore, directly recorded, information about Anglo-Saxon landholding being accommodated to the feudal structure of 1086, with potentially misleading results.

The structure of fiefs within counties is examined in the introductory chapters to the Domesday survey for each county in the Victoria County History and Alecto editions of Domesday Book; the chapters by J.H. Round in the Victoria County History, and those by Richard P. Abels and Chris P. Lewis for Alecto are particularly valuable in this respect. The analysis of the fiefs of the tenants-in-chief in Oxfordshire by Reginald Lennard, Rural England, 1086-1135: a study of social and agrarian conditions (1959), is one of the best of its kind.

See also codes for landowners.