The Norman Conquest completely changed the face of England. William replaced much of the nobility of England with Normans, and French not English became the language of the royalty. This would ultimately change the English language, which would become a mixture of both German and French.
With a Duke of Normandy as King of England, it created an unusual relationship between England and France. William and his successors were at the same time king of their own nation as well as vassal to a foreign King. As the English continued to gain more land under French control this would lead to increasing conflict and ultimately to the Hundred Years War starting in the 14th Century.
William greatly changed the English system of government. He brought the system of feudalism with him to England, as well as the Norman style of castle building. Prior to William there were few castles in England, after his coming they would litter the landscape.
One of the most historically significant acts of William’s reign was the composition of the Domesday Book. This was a complete census of England, both its population and their property, so that he could more properly tax them. This has given historians a strong insight into the lives of the English at this time, and it is the most comprehensive book of its kind in existence for this period of English history.
1066 was a tumultuous year, the beginning of a conquest that would last for years as William secured his seat on the throne. Forevermore the Kings and Queens of England would be descended from the Normans. The language would change drastically, as would the government of England. The ramifications of 1066 last up until this day. It is truly a turning point in English history and the history of the world.