The holy grail of data: it's Domesday, online

William the Conqueror's great census is made available free on the internet

'Not even one ox, nor one cow, nor one pig was left out.' But what William the Conqueror didn't have in the Domesday Book was an easy way of searching its reams of data. It has taken more than 900 years, but at last the internet has provided a solution.

An academic at Hull University has produced the world's first complete, freely available online version.

Professor John Palmer, whose work on the Domesday Book stretches back 25 years, has transformed its handwritten parchment pages into a database with searchable indexes, a detailed commentary and the ability to organise all its statistics in a tabulated format.

The Domesday Book, the oldest and most famous public record, was based on the 1086 great survey of England which investigated 'how the country was occupied, and with what sort of people... how much each had... and how much it was worth'. It covered 13,418 settlements south of the rivers Ribble and Tees.

As with the Last Judgment, all were called to account - hence the name, Domesday, Day of Judgment. There would be nothing like it in England again until the censuses of the 19th century.

But for nearly 1,000 years it has been inaccessible to most people and difficult to understand. There are costly CD-Rom translations, and the National Archives provides online searches, but Palmer set out to create a new format to bring the book into the digital age. Whereas the original has information listed under headings, Palmer has coded and tagged terms so they can be automatically retrieved and analysed. His software makes it possible to isolate certain variables and conduct several searches at once. The results can be displayed as a map, table or translated text, or as a combination of formats.

The three-year project was funded by a £250,000 grant from the Arts and Humanities Research Council.

Palmer, who worked on the project with his son, Matt, said: 'My interest in Domesday began in about 1980 as a teaching project. My son was getting interested in computing at the same time. It developed into a research <interest for the 900th anniversary in 1986, but computers weren't powerful enough then. In the mid-Nineties, the improvements in computers revived my interest and I managed to get some funding.'

Written in Latin, the Domesday Book is the starting point of history for the majority of towns and villages in England. It lists places, landowners and tenants, tax assessments, cultivated land, numbers of oxen and plough teams, property values, legal claims, illegal activity and social classes such as freemen, villeins, smallholders, cottagers, slaves, priests and burgesses.

The total value of all property in England in 1086 was calculated at £75,000 - which in today's money would be £1 trillion. The dozen wealthiest individuals were each richer than any later billionaires in English history, with fortunes ranging from the equivalent of £56bn to £104bn today.

Palmer said: 'No English medieval historian can ignore the book because it's such an important source for social and economic medieval history. It's like a giant skyscraper surrounded by mud huts in terms of significance. If you want to know how many pigs there were in each county, the Domesday Book is the best record there is of who owned what, right down to people who owned a few shillings.

'Anyone who looks at it is stunned by the speed and coverage: it was completed within a year and Englishmen were generally in awe of it. All through the Middle Ages it was used as the permanent record: there were all sorts of appeals to it to resolve property disputes.'

· The Domesday Book is available online via Essex University's Arts and Humanities Data Service at