Nihonjinron (日本人論, "theories/discussions about the Japanese") is a genre of texts that focus on issues of Japanese national and cultural identity. The concept became popular after World War II, with books and articles aiming to analyze, explain, or explore peculiarities of Japanese culture and mentality, usually by comparison with those of Europe and North America. The literature is vast, ranging over such varied fields as sociology, psychology, anthropology, history, linguistics, philosophy, biology, chemistry and physics so in addition to the common generic word nihonjinron, a variety of topical subgenres exist, divided up by specific theme or subject-matter. For example: