The generic approach to literature attempts to formulate terms for categorizing and organizing texts of the same literary kind. This activity has important implications for the evaluation of individual texts by insisting that texts be judged according to the criteria appropriate to the genre to which they belong. Texts are grouped into genres according to a variety of generic principles: formal structure, distinctive subject matter, historical status, shared allusions or motifs, linguistic conventions, and the like. There are particular problems associated with the work of defining or comprehending the novel as a genre. The popularity of the novel, which has caused it to overtake, and in many cases to subsume, other literary forms, has produced a definition of the novel that is so comprehensive as to be useless in a generic sense. The novel is commonly regarded as an extended fictional prose narrative. This definition indicates the extent to which the novel has subsumed other genres of prose fiction, but the result is that such a comprehensive genre has only a weak sense of unity.