Some people feel that wikis are radical because they allow you to edit other people’s contributions. They might feel more at ease if they could just add a comment somewhere. Enter Discussion Pages.
Discussion pages allow you to carry on, well, discussions, off the main wiki page. Think of it like the "comments" section on a blog, or even like a forum.
The obvious benefit of using discussion pages is it keeps the page content nice and clean, while allowing side-bar conversations and even brainstorming to take place "behind the scenes" in a manner of speaking.
When set, this prefix identifies discussion pages, and it enables comments*. On the non-discussion pages, you will find a link in the footer called "Discuss <PAGE>" (with <PAGE> being the current page name). This will lead to the discussion page. Discussion pages will have a link back to the original page. Discussion pages can be edited just like other pages. At the same time, they have a comment textarea at the bottom, where your readers can add a comment and sign with their name (and optional URL).
Default: 'Add your comment here.'
This option contains the default text in the comment form on discussion pages.