This paper gives an outline of the Modular Theory of Writing Systems by answering the question: what are the elements or modules that are necessary for a writing system to work? A writing system is a notational system for a natural language. Based on this characterization, it is obvious that a necessary component of a writing system is a specific language system. What eventually constitutes a writing system in addition to this language system is a device that, put simply, relates units of a language system to units of a script. This component is termed ‘graphematics’ in the present framework and is regarded as a necessary module of a writing system. Above that, another typical component of writing systems, namely ‘systematic orthography’, applies to the ‘graphematic solution space’ and restricts the spelling possibilities of specific words in accordance to their belonging to a specific level of the vocabulary of the language. Supplemented by reflections on the status of scripts as well as of IPA as a writing system, an answer is finally given to the pertinent question how spoken language and written language are related to each other. The answer is that this relation is of a considerably indirect nature.