Middle English developed out of Late Old English, seeing many dramatic changes in its grammar, pronunciation and orthography. Writing customs during Middle English times varied widely, but by the end of the period, about 1470, aided by the invention of the printing press, a standard based on the London dialect (Chancery Standard) had become established. This largely forms the basis for Modern English spelling, although pronunciation has changed considerably since that time. Middle English was succeeded in England by the era of Early Modern English, which lasted until about 1650. Also, by that time the Scots language was developing from a variant of the Northumbrian dialect (prevalent in northern England and spoken in southeast Scotland).
During the Middle English period many Old English grammatical features were simplified or disappeared. Noun, adjective and verb inflections were simplified, a process that included the reduction (and eventual elimination) of most grammatical case distinctions. Middle English also saw a mass adoption of Norman French vocabulary, especially in areas such as politics, law, the arts, religion and other courtly language. Everyday English vocabulary remained mostly Germanic, with Old Norse influence becoming apparent. Significant changes in pronunciation took place, especially for long vowels and diphthongs, which in the later Middle English period began to undergo the Great Vowel Shift.
Little survives of early Middle English literature, most likely due to the Norman domination and the prestige that came with writing in French rather than English. During the 14th century, a new style of literature emerged with the works of notable writers such as John Wycliffe and Geoffrey Chaucer, whose Canterbury Tales remains the most studied and read work of the period. Poets wrote both in the vernacular and courtly English.
The latter part of the 11th century was a period of transition from Late Old English to Early Middle English.
The influence of Old Norse certainly helped move English from a synthetic language with relatively free word order, towards a more analytic or isolating language with more strict word order, a deep change at the grammatical level. Both Old English and Old Norse were (and the latter's modern descendants, Faroese and Icelandic, still are) synthetic languages with complicated inflectional word-endings, but the endings were different. The eagerness of Vikings in the Danelaw to communicate with their southern Anglo-Saxon neighbors produced a friction that led to the erosion of inflection in both languages; Old Norse likely had a greater impact on this deep change to Middle and Modern English than any other language. Simeon Potter notes: "No less far-reaching was the influence of Scandinavian upon the inflexional endings of English in hastening that wearing away and leveling of grammatical forms which gradually spread from north to south. It was, after all, a salutary influence. The gain was greater than the loss. There was a gain in directness, in clarity, and in strength".