Markup modules return a bit of markup. Each of these modules live as a subfolder of app/modules/markup/
. Most websites will have many markup modules.
In this sample file website, the content for this page and all the Portfolio pages and the section on the Home page comes from the high-level-module which is found at markup/high-level-module/
. Each of those pages call the same module which returns the same data within slightly different markup depending on the needs of the page.