Major differences between British and American English with respect to vocabulary.
This is one of a series of articles about the differences between American English and British English, which, for the purposes of these articles, are defined as follows:
· American English (AmE) is the form of English used in the United States. It includes all English dialects used within the United States.
· British English (BrE) is the form of English used in the United Kingdom. It includes all English dialects used within the United Kingdom.
Written forms of American and British English as found in newspapers and textbooks vary little in their essential features, with only occasional noticeable differences in comparable media (comparing American newspapers with British newspapers, for example). This kind of formal English, particularly written English, is often called 'standard English'.
The spoken forms of British English vary considerably, reflecting a long history of dialect development amid isolated populations. Dialects and accents vary not only among the countries in the United Kingdom, England, Northern Ireland, Scotland and Wales, but also within these individual countries.
There are also differences in the English spoken by different groups of people in any particular region. Received Pronunciation (RP) has traditionally been regarded as proper English; this is also referred to as "BBC English" or "the Queen's English". The BBC and other broadcasters now intentionally use a mix of presenters with a variety of British accents and dialects, and the concept of "proper English" is now far less prevalent.
An unofficial standard for spoken American English has also developed, as a result of mass media and geographic and social mobility, and broadly describes the English typically heard from network newscasters, commonly referred to as non-regional diction, although local newscasters tend toward more parochial forms of speech.  Despite this unofficial standard, regional variations of American English have not only persisted but have actually intensified, according to linguist William Labov.
Regional dialects in the United States typically reflect the elements of the language of the main immigrant groups in any particular region of the country, especially in terms of pronunciation and vernacular vocabulary. Scholars have mapped at least four major regional variations of spoken American English: Northern, Southern, Midland, and Western. After the American Civil War, the settlement of the western territories by migrants from the east led to dialect mixing and levelling, so that regional dialects are most strongly differentiated in the eastern parts of the country that were settled earlier. Localized dialects also exist with quite distinct variations, such as in Southern Appalachia and New York.
British and American English are the reference norms for English as spoken, written, and taught in the rest of the world. For instance the English-speaking members of the Commonwealth often closely follow British English forms while many new American English forms quickly become familiar outside of the United States. Although most dialects of English used in the former British Empire outside of North America are, to various extents, based on British English, most of the countries concerned have developed their own unique dialects, particularly with respect to pronunciation, idioms and vocabulary. Chief among other English dialects are Canadian English, based on the English of United Empire Loyalists who left the 13 Colonies, and Australian English, which rank third and fourth in number of native speakers.