The English language we now know would not have been the same if it was not for the events that happened in 1066. In 1066, the Duke of Normandy, William sailed across the British Channel. He challenged King Harold of England in the struggle for the English throne. After winning the battle of Hastings William was crowned king of England and the Norman Kingdom was established. Norman-French became the language of the English court. At the beginning French was spoken only by the Normans but soon through intermarriage, English men learnt French. Some 10,000 French words were taken into English language during the Middle English period and about 75% of them are still in use.
One of the most obvious changes that occurred after the Norman conquest was that of the language: the Anglo-Norman. When William the Conqueror was crowned as king of England, Anglo-Norman became the language of the court, the administration, and culture. English was demoted to more common and unprestigious usages. Anglo Norman was instated as the language of the ruling classes, and it would be so until about three centuries later. But not only the upper classes used French, merchants who travelled to and from the channel, and those who wanted to belong to these groups, or have a relationship with them, had to learn the language.
These events marked the beginning of Middle English, and had an incredible effect in the way English is spoken nowadays. Before the Norman conquest, Latin had been a minor influence on English, but at this stage, some 30000 words entered the English language, that is, about one third of the total vocabulary. But vocabulary was not the only thing that changed in the English language. While Old English had been an extremely inflected language, it now had lost most of its inflections.
The influence of the Normans can be illustrated by looking at two words, beef and cow. Beef, commonly eaten by the aristocracy, derives from the Anglo-Norman, while the Anglo-Saxon commoners, who tended the cattle, retained the Germanic cow. Many legal terms, such as indict, jury, and verdict have Anglo-Norman roots because the Normans ran the courts. This split, where words commonly used by the aristocracy have Romantic roots and words frequently used by the Anglo-Saxon commoners have Germanic roots, can be seen in many instances.
In vocabulary, about 10000 words entered the English language at this stage, and more than a third of today’s PdE (Present-day English) words are related to those Anglo-Norman ME (Middle English) words.
English pronunciation also changed. The fricative sounds [f], [s], [Ɵ] (as in thin), and [ʃ] (shin), French influence helped to distinguish their voiced counterparts [v], [z],  (the), and [ƺ] (mirage), and also contributed the diphthong [oi] (boy).
Grammar was also influenced by this phenomenon especially in the word order. While Old English (and PdE in most of the occasions) had an Adj + N order, some expressions like secretary general, changed into the French word order, that is, N + Adj.
English has also added some words and idioms that are purely French, and that are used nowadays.
Since French-speaking Normans took control over the church and the court of London. A largest number of words borrowed by the government, spiritual and ecclesiastical (religious) services. As example – state, royal (roial), exile (exil), rebel, noble, peer, prince, princess, justice, army (armee), navy (navie), enemy (enemi), battle, soldier, spy (verb), combat (verb) and more. French words also borrowed in English art, culture, and fashion as music, poet (poete), prose, romance, pen, paper, grammar, noun, gender, pain, blue, diamond, dance (verb), melody, image, beauty, remedy, poison, joy, poor, nice, etc. Many of the above words are different from modern French in use or pronunciation or spelling.
Thus, the linguistic situation in Britain after the Conquest was complex. French was the native language of a minority of a few thousand speakers, but a minority with influence out of all proportion to their numbers because they controlled the political, ecclesiastical, economic, and cultural life of the nation.