The linguistic term codification refers to the methods by which a language is standardized. These methods include the creation and use of dictionaries, style and usage guides, traditional grammar textbooks, and the like.
"Standardization aims to ensure fixed values for the counters in a system," wrote James and Lesley Milroy in "Authority in Language: Investigating Standard English." "In language, this means preventing variability in spelling and pronunciation by selecting fixed conventions uniquely regarded as 'correct,' establishing 'correct' meanings of words… uniquely acceptable word forms (he does is acceptable, but he do is not) and fixed conventions of sentence structure."
The term codification was popularized in the early 1970s by linguist Einar Haugen, who defined it as a process that leads to "minimal variation in form" ("Dialect, Language, Nation," 1972).
The Evolution of English
Codification is an ongoing process. The English language evolved over centuries from Old English to Middle English after the Norman Conquest in 1066 to Modern English in about the mid-15th century. For example, different word forms were dropped, such as having nouns with different genders or additional verb forms. The proper order for words in a sentence coalesced (subject-verb-object) and variations (such as verb-subject-object) pretty much disappeared. New words were added, such as 10,000 of them being incorporated from French after the conquest. Some of the duplicate words changed meanings, and some were lost altogether. These are all examples of how the language has codified.
Spellings and meanings continue to change and be added to the dictionary today, of course, but "the most important period of codification in English was probably the 18th century, which saw the publication of hundreds of dictionaries and grammars, including Samuel Johnson's monumental Dictionary of the English Language (1755) in Great Britain and Noah Webster's The American Spelling Book (1783) in the United States" ("Routledge Dictionary of English Language Studies," 2007).
During the language's evolution, Dennis Ager wrote, in the "Language Policy in Britain and France: The Processes of Policy," "three influences were… paramount: the king's English, in the form of the administrative and legal language; literary English, in the form of the language accepted as that used by great literature-and for printing and publishing; and 'Oxford English,' or the English of education and the Church-its main provider. At no point in this process was the State openly involved."
"Codification also affected the spoken form of the standard language. 'Received pronunciation' was codified through the influence of education, particularly that of the 19th-century public schools, followed from the early 20th century by cinema, radio and television ('BBC English'). Nonetheless it is estimated that only 3-5 per cent of the population of Britain speak received pronunciation today… and hence this particular form of the language is 'accepted' by society only in the sense that it is widely understood."
Even though English is a flexible language, continually borrowing words from other languages (an estimated 350 different languages, in fact), adding words, definitions, and spellings to the dictionary, the basic grammar and pronunciation have remained relatively stable and codified.