The hide was both a unit of assessment and a peasant landholding unit found in most counties outside the Danelaw. The word hide ultimately derives from the Old English hid, meaning the amount of land which would support one household, notionally 120 acres in most counties, though hides of 40, 48 and 60 acres have been identified elsewhere, particularly in the south-west.
However many fiscal acres a hide contained, these would bear a variable relationship to the customary acres on the ground. Since customary acres were normally composed of scattered furlong strips whose size varied according to the nature of the soils and the shape of the fields, hides could vary in size from area to area, or even within the same manor, however many acres they contained.
Although the original meaning of the hide was the amount of land needed to support one peasant household, by the eleventh century peasant holdings of this size were uncommon, the virgate being the norm for villagers. The detailed evidence of the Domesday text for Middlesex does, however, show that individual peasants still occasionally had holdings of this size.
Despite variations in size, however, individual hides could, like other peasant holdings, remain fixed in size over generations, even centuries, their integrity maintained by the power of the lord or the customs of the manor. They provided the stable base for both the manorial and the assessment systems.
For more detail, see Frederic Seebohm, The English village community (fourth edition, 1915); J.H. Round, Feudal England (1895); F.W. Maitland, Domesday Book and beyond (1897); the note to DEV 1,4 in Domesday Book, vol. 9: Devon, edited by Caroline and Frank Thorn (2 vols., Phillimore, 1985), which can also be found online at: https://hydra.hull.ac.uk/resources/hull:535; and Rosamond Faith, The English peasantry and the growth of lordship (1997).