In 1085, William the Conqueror ordered that a survey be made of all land holdings in his domain. The result was the "Domesday" or Doomsday Book", published in two volumes in 1086. The books provided information regarding the ownership, state of cultivation, and area of cultivation of lands, the population of various classes of vassals (freemen, villeins, cotters, and serfs), and for some areas, livestock. Its purpose was evidently to provide a census of the ownership and potential for taxation throughout the kingdom.
One volume covered Essex, Norfolk and Suffolk. The other volume covered the rest of the kingdom, except London and Winchester, where no survey was done, and Northumberland, Cumberland, Durham, and Westmorland, where the king's authority did not extend.
Various explanations have been put forward for the title, with the most generally accepted being that on account of its completeness, it was a "day of judgment" for the facts that it contained.