Regional and Social Dialects

We distinguish between  regional and social dialects. If the differences are based on the biography, then we identify what are called regional dialects.They are studied by the discipline called dialectology. One of the fundamental findings of sociolinguistics is that class and variety are related. Members of the working class tend to speak less standart language, while middle and upper classes will speak closer to the standart language. So besides biography there exists another important factor-social class. Therefore we may speak of social dialects or sociolects as distinct from regular language dialects.