PmWiki

PmWiki is a wiki engine, or software for running a wiki. It was created by Patrick McChaud in the PHP scripting language and is available under the GNU GPL.

PmWiki was designed to be incredibly easy to install and use, only requiring a PHP backend. It can support using database software like MySQL, but it is not required. It has some similarities to MediaWiki in regards to markup, though it is is much closer to UseModWiki and the original WikiWikiWeb in terms of syntax and appearance. Wiki links are done in CamelCase, though MediaWiki styled "free links" are also supported.

PmWiki stores pages as "flat files", meaning each page is saved as a literal document file on the server. A wiki with a database saves pages as blobs of text in a database, separating the differences in page revisions only, which makes it easier to restore specific versions of a page at the cost of some page load speed. By contrast, flat files make page loads much faster, but restoring specific revisions of pages requires much more manual effort.

Like MediaWiki, PmWiki has support for namespaces, has its own extensions (called "cookbook files"), and supports custom skins. However, while PmWiki allows for a much higher level of customization during setup of skins and extensions, it also requires a higher manual knowledge of wiki configuration than MediaWiki. It's also easier to hack the core files of PmWiki, but this can seriously degrade stability and should only be attempted by those with lots of PHP experience.

One of the most well known wikis that use PmWiki would be TV Tropes, which uses a highly modified version of the PmWiki engine.

You find PmWiki (and learn more about it) at the PmWiki website.