The sociology of language is defined as the study of the interaction between the use of language and the social organization (in terms of shared norms) of behavior. Some basic sociolinguistic concepts are reviewed (such as language-dialect-variety, language attitudes, speech community). A distinction is made between micro and macro approaches. Societal differentiation and repertoire range are dealt with, as well as societal bilingualism, language maintenance and language shift, and socio-cultural language constraints. Possible applications are indicated.