Only a few centuries ago, the English language consisted of a collection of dialects spoken mainly by monolinguals and only within the shores of a small island. Now it includes such typologically distinct varieties as pidgins and Creoles, ‘new’ Englishes, and a range of differing standard and non-standard varieties that are spoken on a regular basis in more than 60 different countries around the world (Crystal 1985). English is also, of course, the main language used for communication at an international level.

Such diversity of form and function within what is nevertheless still thought of as a single language offers a unique opportunity to analyse and document the linguistic variation and change that is occurring on a far greater scale – as far as we know – than has ever happened in the world's linguistic history. It also allows us to investigate the relationship between language and the community in which it is used from a broader perspective than is usual. Academic disciplines tend to fragment into separate specialist fields: dialectology, bilingualism, pidgin and creole studies, and sociolinguistics, for example, are often treated as if they are relatively self-contained areas of study. All four of these fields, however, share the problems of describing and explaining linguistic variation, though the nature of the variation may differ; and all four fields investigate essentially the same social and educational issues arising from community attitudes that assign high prestige to some languages, or varieties of a language, and low prestige to others (see also Rickford 1988).