The language we now call English should really be called the “languages we know as English” since it is a mixture of many languages. In this mixture can be gleaned the history of invasion and settlement of the British Isles.
“English” was brought to this small cluster of islands in the 5th and 6th centuries ad, by seafarers from Denmark and other places in Scandinavia and from present-day Germany and the Netherlands. These immigrants spoke related dialects of the Germanic branch of the Indo-European language family.
By ad 600 these dialects developed into what we call Old English or Anglo-Saxon. Words of Anglo-Saxon origin tend to be just one or two syllables. They relate to such topics as the human body, animals, farming, the weather, family relationships, colours, landscape features, and human activities such as cooking, eating, sewing, hunting and carpentry. Examples include abide, above, ale, alive, apple, awake, axe and dwell. Many place names in England have Scandinavian names, for example, Grimsby, Whitby, Derby, Rugby, and Thoresby, which end in “–by”, meaning farm or town in Danish.
In 1066, the Norman king, William the Conquerer, invaded England. Many Norman French words entered the language after this. In general, the Normans were the nobility, while the native English were their servants. The names of domestic animals and their meats show this relationship. The animal name is English (“cow”, “sheep”, “pig”) while the names of the meats from these animals are French (“beef”, “mutton”, “pork”). Other words borrowed from Norman French. These can be grouped into several types, for example Legal terms (“adultery”, “slander”), military words (“surrender”, “occupy”), and royal words (“chivalry”, “majesty”).
Of course Latin was also used as the church held a prominent place in society of that time. Latin was also a “lingua franca” (a common language) as people travelled outside Britain. Many Latin words appear unchanged in modern English such as apparatus, appendix, aquarium, diploma and distributor.
William Caxton set up the first printing press in Britain at the end of the 15th century. This meant that English was able to become more standardized in spelling and grammar although this would still take a couple of centuries. By the 17th century, most of this standardization was in place and we can still read the language of that time today.