Intertextuality is the shaping of a text's meaning by another text. Intertextual figures include: allusion, quotation, calque, plagiarism, translation, pastiche and parody. Intertextuality is a literary device that creates an 'interrelationship between texts' and generates related understanding in separate works ("Intertextuality", 2015). These references are made to influence the reader and add layers of depth to a text, based on the readers' prior knowledge and understanding. Intertextuality is a literary discourse strategy (Gadavanij, n.d.) utilised by writers in novels, poetry, theatre and even in non-written texts (such as performances and digital media). Examples of intertextuality are an author's borrowing and transformation of a prior text, and a reader's referencing of one text in reading another.
Intertextuality does not require citing or referencing punctuation (such as quotation marks) and is often mistaken for plagiarism (Ivanic, 1998). Intertextuality can be produced in texts using a variety of functions including allusion, quotation and referencing (Hebel, 1989). However, intertextuality is not always intentional and can be utilised inadvertently. As philosopher William Irwin wrote, the term "has come to have almost as many meanings as users, from those faithful to Kristeva's original vision to those who simply use it as a stylish way of talking about allusion and influence".
Intertextuality and intertextual relationships can be separated into three types: obligatory, optional and accidental (Fitzsimmons, 2013). These variations depend on two key factors: the intention of the writer, and the significance of the reference. The distinctions between these types and those differences between categories are not absolute and exclusive (Miola, 2004) but instead, are manipulated in a way that allows them to co-exist within the same text.
Obligatory intertextuality is when the writer deliberately invokes a comparison or association between two (or more) texts. Without this pre-understanding or success to 'grasp the link', the reader's understanding of the text is regarded as inadequate (Fitzsimmons, 2013). Obligatory intertextuality relies on the reading or understanding of a prior hypotext, before full comprehension of the hypertext can be achieved (Jacobmeyer, 1998).