Sociolinguistics is the branch of linguistics that is concerned with language in social contexts - how people use language, how it varies according to context and over time, how it contributes to users' sense of identity, and so on.
Sociolinguistics covers a wide variety of subdisciplines. It can involve the study of linguistic variation, language attitudes, pragmatics, discourse analysis, multilingualism, creolistics, applied linguistics, language planning, literacy studies and language and gender. It also overlaps with other fields such as communication studies, sociology, social anthropology and media studies.
Sociolinguists will typically be familiar with more theoretical study of language, and may well discuss language using theoretical definitions - for example, they may study how the syntax and phonology of languages vary according to different social factors. A famous sociolinguistic study conducted by William Labov, for example, focused on how New Yorkers varied in their use of the r segment in phrases such as fourth floor, finding that the presence or absence of r correlated with social context - in this case, the prestige of department stores where different speakers worked. This use of the apparatus of theoretical linguistics and the concern with language itself both distinguish sociolinguists from sociologists, who may study language to understand how societies themselves work.
- Labov (1969; 1972).