Wiki

A wiki is a collection of collaboratively authored web documents.
A wiki page is a web page to which everyone in the Moodle web can contribute, right in the browser, without needing to know HTML or special wiki code.
A wiki starts with one front page. Each author can add other pages to the wiki by creating a link to a page that doesn’t exist yet.

How to set up a wiki and contribute to it.

How to add an image to a wiki

Guides from Moodle Docs

Wiki