The practice of simultaneously programming and writing documentation is such a fashion that the result is designed to be read by humans while producing "real" computer code. The term was invented by D. Knuth during his development of the TeX system. Since the documentation is intermingled with the source code or pseudo-code, systems for literate programming are often referred to as WEB systems, following Knuth's nomenclature. This use of the term WEB considerably pre-dates its use in reference to the World Wide Web (WWW). It is a style that is quite suited to teaching purposes.