The main information about Southern and Northern American English

There is little question that English is the most widely taught, read, and spoken lan¬guage that the world has ever known. It may seem strange, on some moments' reflection, that the native language of a relatively small island nation could have developed and spread to this status [1; 225].
It seems, then, that while the criterion of mutual intelligibility may have some rel¬evance, it is not especially useful in helping us to decide what is and is not a language. In fact, we have to recognise that, paradoxically enough, a language is not a particularly linguistic notion at all.