This chapter discusses definitions of discourse and discourse analysis, including "little d" discourse referring to language in context and "big D" discourse as specialized language of social groups. It outlines structural and functional approaches to discourse analysis and describes various disciplines and main approaches. Context and models of communication are examined, including Hymes' 16 contextual features and Halliday's three parameters of context. The development of the concept of communicative competence from Hymes to Canale and Swain to Celce-Murcia is summarized.