Wiki’s are a form of content management system, where the content can be edited on the web directly. Typically wiki’s are open to anyone to edit, although some (such as this one) can only be edited by authorised users.

A Wiki differs from most others CMS’s by encouraging editing, quickly and in-situ usely with a light-weight markup system for styling the content. This Wiki uses Textile for formatting.

Yaki is a Wiki/Blogging platform with some really nice features. The main one is that it is extremely light weight. Pages and posts are simple files, with a set of headers at the top that define the details (tags, dates, etc). Mirroring and backups of the site can then be done with any file synchronisation tool.

I toyed with using it on this site, since I wanted to add Wiki-Style behaviour, but ended up using my old favourite for more complex sites, Drupal.