Critical Discourse Analysis, or CDA is an interdisciplinary approach to the study of text and talk, which views "language as a form of social practice" (Fairclough 1989: 20) and attempts "to unpack the ideological underpinnings of discourse that have become so naturalized over time that we begin to treat them as common, acceptable and natural features of discourse" (Teo 2000).
Norman Fairclough's books, Language and Power (1989) and Critical Discourse Analysis (1995), articulate a three-dimensional framework for studying discourse, "where the aim is to map three separate forms of analysis onto one another: analysis of (spoken or written) language texts, analysis of discourse practice (processes of text production, distribution and consumption) and analysis of discursive events as instances of sociocultural practice" (1995: 2).
In addition to linguistic theory, the approach draws from social theory--and contributions from Marx, Gramsci, Althusser, Habermas, and Foucault--in order to examine ideologies and power relations involved in discourse. Fairclough notes "that language connects with the social through being the primary domain of ideology, and through being both a site of, and a stake in, struggles for power" (1989: 15).
Notable researchers include Norman Fairclough, Paul Chilton, Teun van Dijk, Christina Shaffner, Ruth Wodak, Peter Teo, Roger Fowler, Gunther Kress, and Robert Hodge.