Comment by toast0

> I’d love to know what you think documentation means.

I'd say effective documentation lets the user know enough about the system that they can work on the system without needing to contact the previous person (or people) working on the system. Or at least, so they can get started and only ask 'good' questions.

Something like descriptions of what the system is supposed to do, what it actually does if it differs significantly :D, maybe motivations. Descriptions of the data, and like where does it come from, where does it go, where did it come from (Cotton-Eye Joe?). If the system runs into problems often, a list of common issues and how to fix them, etc.