Writen language:

A written language is the representation of a language by means of a writing system. Written language is an invention in that it must be taught to children, who will instinctively learn or create spoken or gestural languages.
A written language exists only as a complement to a specific spoken or gestural language, and no natural language is purely written. However, extinct languages may be in effect purely written when only their writings survive.
Written languages evolve more slowly than corresponding spoken languages. When one or more registers of a language come to be strongly divergent from spoken language, the resulting situation is called diglossia. However,
such diglossia is often considered as one between literary language and other registers, especially if the writing system reflects its pronunciation.