Differences between British and American English

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 the dialects of English used in the former British Empire are often, 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 them are Canadian English and Australian English, which rank third and fourth in number of native speakers.