In many speech communities two or more varieties of the same language2
are used by some speakers under different conditions.Perhaps the most
familiar example is the standard language and regional dialect as used, say,
in Italian or Persian, where many speakers speak their local dialect at home
or among family or friends of the same dialect area but use the standard
language in communicating with speakers of other dialects or on public
occasions.There are, however, other, quite different examples of the use of
two varieties of a language in the same speech community.