American English is a dialect of the original language spoken in Great Britain which is used in the United States. American English itself consists of a number of different dialects. Distinctive dialects of American English include those spoken in the South, New England, and New York City, to name only a few. Even these dialects can be broken down further into distinctive dialects, such as the English spoken in Brooklyn, or that spoken in Boston.
The use of English in the United States was inherited as a result of British colonization of the country which at the time was partly a British colony. The first wave of English-speaking settlers arrived in North America in the 17th century. During that time, there were also speakers in North America of Dutch, French, German, Spanish, Swedish, Scots, Welsh, Irish, Scottish Gaelic, Finnish, as well as numerous Native American languages. To a certain extent, the American dialect spoken commonly throughout the USA comes from the intertwining of many of these languages and dialects.
As American society became more productive and efficient than the British, Americans began to emphasize economy in language also. President Teddy Roosevelt, for example, endorsed an effort to remove cumbersome and illogical spellings from the English language as used in America. The Chicago Tribune also embarked on its own effort to simplify spelling and make it more phonetic. These efforts were illustrative of a cultural movement away from arcane British English spellings and expressions.
Today American English is simpler and more phonetic than British English. Sometimes as an expression of anti-American sentiment, however, non-Americans will insist that use of arcane British English is exclusively proper English. The predominantly liberal Wikipedia suffers from an excess of British English, far beyond the proportional country of origins of contributors and readers.