Not only did the Vikings introduce new words to Britain but they also changed English word structure. Nouns in Old English used to have prefixes and/or suffixes to describe various cases. Nominative (NOM) case expressed a noun with a finate verb – a subject with mood, tense, time etc. Objects in a sentence could have a genitive (GEN) case to express possession, a dative (DAT) case to express movement as in ‘to’ or ‘for’ and an accusative (ACC) case to make a word an object.
Old English: Ϸæt folc geaf cyninge aϷas
Trans: that people-NOM gave king-DAT oaths-ACC
Modern English: The people Gave oaths to the king.
When the Vikings invaded and settled in England they helped to change English from a synthetic language to a analytic language, meaning Old English broke off its cases from the nouns and turned them into individual words such as ‘a, the, to, for, with’ etc. The reason why this happened is very simple – because of practicality. In essence Old Norse and Old English were similar because they were both Germanic languages. However, the English prefixes and suffixes complicated words and made it hard for the English and Norsemen to communicate. So in order to talk to each other the English had to simplify when they spoke with a Norseman by dropping or breaking up noun additives. Soon this became the norm and English evolved into an analytic language. As people wrote the way they spoke in those days, the spelling and structure of written words also changed therefore cementing the new English. Today we speak similar to the way the old Englishmen had to in order to communicate with the Norse.
Gelderen, E. V, A History of the English Language, John Benjamin B.V. Amsterdam: 2006 (p.24)