Evidence against the autonomy and homogeneity of the linguistic system. Domains of sociolinguistics. Regional and social variation. Dialects and sociolects. Urban dialectology. Language and social stratification. Communicative situations and registers. Languages in contact. Multilingualism, diglossia, code switching and code mixing. Lingua Francas, pidgins and creoles. Majority and minority languages. Language maintenance and language loss. Linguistic variation and language change. Language and social inequality. The case of sexist language. Sociolinguistic attitudes. Some basic methodological concerns of sociolinguistic research.