This is a relly broad question. Literary criticism is as old as literature itself. In the past, literary criticism was primarily conceived as the study of great literature. Criticism was therefore mostly about passing value judgements in literature and about creating a canon of texts that were the best and the greatest. This conception of criticism has been challenged by the so-called "sociological turn" in literary studies that took place in the 1960s with the introduction of cultural studies. Critics increasingly pointed out that the works included in the canon reflected the predominant ideological views of a given era. The greatness of a literary work and of the canon in general could not be established objectively, but was socially constructed. Since the introduction of Cultural Studies, western criticism has been less oriented toward value and more toward analysing the connections between literary texts and society. In particular, the categories of race, gender and class have constituted a paradigm to analyse both contemporary and past literature.