Citationality is often seen as a typical feature of postmodernism, especially in its pop culture manifestations (consider how frequently a television show like The Simpsons or Mystery Science Theater 3000 makes use of quotes and citations).
In critical theory, citationality sometimes refers to Jacques Derrida's notion of iterability from his essay "Signature Event Context",[1] where he argued that the essential feature of a signature was that it had a recognizable form and could be repeated.
In other words, although a signature is supposed to testify to the presence of an authentic original intention, it simultaneously sets up the possibility of an inauthentic copy.
Derrida's concept—which he denies is a concept simply because from the moment that the concept enters the game, it has become motivated—emerges from his engagement with J. L. Austin's problematic claim that a "nonserious" performative utterance, as uttered in a play or a poem, say, is "parasitic" upon the true performative and cannot be considered legitimate.
As Derrida recognizes, this is not only a non-problem—the actors are not thereby married, obviously, but the characters are—but the very nature of citing, reiterating, reusing a phrase, reperforming a performative utterance is at the heart of the communicative function of language.