Answers.

What was the Domesday Book?

The Domesday Book is a record of an enormous survey carried out in England BY King William I (the Conqueror), and it was completed in the year 1086. It was similar to a census as it is carried out nowadays and its main purpose was to have a record of all land, property and people in the country so that taxes could be raised. 
It is extremely useful to modern day historians because it lists all the towns and villages of the time and so gives an idea of how old some of them are. 
The Domesday Book is one of Medieval England's greatest treasures. 
The Domesday Book is closely linked with William the Conqueror's attempt to dominate Medieval England. Along with a string of castles throughout England, the Doomsday Book was to give William huge authority in England. 
To further extend his grip on England, William I ordered that a book be made containing information on who owned what throughout the country. This book would also tell him who owed him what in tax and because the information was on record, nobody could dispute or argue against a tax demand. 
This is why the book brought doom and gloom to the people of England - hence "Domesday Book". 
William ordered the survey of England to take place about twenty years after the Battle of Hastings. 
The Saxon Chronicle states that it took place in 1085, while other sources state that it was done in 1086. The whole survey took less than a year to complete and the books can be found in the Public Records Office. The Domesday Book forms a remarkable record of the state of England in the mid-1080's. A sample of the questions asked is found at Ely Cathedral.
It was a census of people and property in England ordered by King William in the 11th century.

What was the Domesday Book and how did it change England?

It changed England as it gave a clear understanding of the taxation systems then and now.

Why is the Domesday book called Domesday?

It's called the Domesday book because the word 'Dom' means reckoning, or accounting in the old English translation. It means descendant in modern English.

What was the Domesday book used for?

The Domesday Book is a survey of all of England. William the conqueror created the Domesday Book, to keep a record of all the land in England, when the Danish army were going to invade England. The barons went and asked the villages about how much land they had, price when king Edward was alive and the price now. All of this information was kept as a record for William. The knights would threaten to kill anyone who lies. When William had the book he was able to take lands away from people when he needed it and he knew how much the land was worth. William also was able to know how much tax to charge because the more it was worth the more taxes they had to pay.