What is the aspect of language that deals with writing but not speaking called?

The aspect of language that deals with writing but not speaking is called orthography.

Here's why:

* Orthography refers to the conventional spelling system of a language. It encompasses the rules and conventions for writing words, including the use of letters, punctuation, and other symbols.

* Speaking involves the production and perception of spoken language, which is governed by different rules of phonology (sound system) and phonetics (sound production).

While writing and speaking are both forms of communication, orthography focuses specifically on the written form of language, independent of its spoken counterpart.