This term is most often used of editors, word processors, and document formatting programs. WYSIWYG `desktop publishing' programs, for example, are a clear win for creating small documents with lots of fonts and graphics in them, especially things like newsletters and presentation slides. When typesetting book-length manuscripts, on the other hand, scale changes the nature of the task; one quickly runs into WYSIAYG limitations, and the increased power and flexibility of a command-driven formatter like TeX, the UNIX system's troff, or CSS becomes not just desirable but a necessity.
Compare YAFIYGI, command line interface
Based on an article from Jargon File.