|Original author(s)||Patrick R. Michaud|
|Initial release||January 2002|
SVN only / nightly
|License||GNU General Public License|
PmWiki is wiki software written by Patrick R. Michaud in the PHP programming language, and since January 2009 it is actively maintained by Petko Yotov under the oversight of Dr. Michaud.
It is free software, licensed under the terms of the GNU General Public License.
PmWiki software focuses on ease-of-use, so people with little IT or wiki experience will be able to put it to use. The software is also designed to be extensible and customizable. The PmWiki philosophy favours writers over readers, doesn't try to replace HTML and supports collaborative maintenance of public web pages.
Besides the usual collaborative features such as content management and knowledge base, PmWiki has been used by companies or groups as an internal communication platform with task management and meeting archives. It is also used by university and research teams.
The PmWiki wiki markup shares similarities with MediaWiki (used by Wikipedia) and has a large number of features not found in other wiki engines however its primary goal is to help with the collaborative maintenance of websites. The PmWiki markup engine is highly customizable, allowing adding, modifying or disabling markup rules, and it can support other markup languages. As an example, the Creole specifications can be enabled.
PmWiki uses regular files to store content. Each page of the wiki is stored in its own file on the web server. Pages are stored in ASCII or Unicode format and may be edited directly by the wiki administrator. According to the author, "For the standard operations (view, edit, page revisions), holding the information in flat files is clearly faster than accessing them in a database..."
PmWiki is designed to be able to store and retrieve the pages' text and metadata in various systems and formats. By default, it does not support databases. However, through plugins, PmWiki can utilize MySQL or SQLite databases for data storage.
PmWiki supports "attachments" (uploads: images or other files) to its wiki pages. The uploads can be attached to a group of pages (default), individually to each page, or to the whole wiki, depending on the content needs and structure. There are PmWiki recipes allowing easier management of the uploaded files, e.g. deletion or thumbnail/gallery creation.
In PmWiki, wiki pages are contained within "wiki groups" (or "namespaces"). Each wiki group can have its own configuration options, plug-ins, access control, skin, sidebar (menu), the language of the content, and interface.
By default, PmWiki allows exactly one hierarchical level of the pages ("WikiGroup/WikiPage"), but through recipes, it is possible to have a flat structure (no wiki groups), multiple nested groups, or sub-pages.
Special wiki groups are "PmWiki", Site, SiteAdmin, and Category which contain the documentation and some configuration templates.
Links to other pages on PmWiki are written in CamelCase, with double square brackets (or none in the case of TV Tropes), and if they are behind another text description (called link text), a vertical line "|" will be separating the page's name and the alternative text. Links to another site are written in square brackets. Endings become part of the text description too. 
Unlike MediaWiki, citations are put with a straight line, followed by a hex sign "#". Headings are also started with exclamation marks, sub-headings have more of them. Lines in a row are considered to be part of the same paragraph, and empty lines will start a new one. Two backward slashes "\\" break the line, and asterisks "*" are used for items in bulleted lists, with many of them producing sub-items. Numbered lists work the same way, except they have hex signs instead of asterisks. Emphasis is done with apostrophes. Double apostrophes mean italics, triple apostrophes mean bolded, and quadruple apostrophes mean bolded and in italics. 
PmWiki offers a skin template scheme that makes it possible to change the look and feel of the wiki or website with a high degree of flexibility in both functionality and appearance.
PmWiki permits users and administrators to establish password protection for individual pages, groups of pages, or the entire site. For example, defined zones may be established to enable collaborative work by certain groups, such as in a company intranet.
Password protection can be applied to reading, editing, uploading to, and changing passwords for the restricted zone. The out-of-the-box installation uses "shared passwords" rather than login names, but a built-in option can enable a sophisticated user/group-based access control system on pages, groups of pages or the whole wiki.
PmWiki can use passwords from config files, special wiki pages, and .htpasswd/.htgroup files. There are also user-based authorization possibilities and authentication via various external sources (e.g. LDAP, forum databases, etc.).
PmWiki follows a design philosophy with the main objectives of ease of installation, maintainability, and keeping non-required features out of the core distribution of the software. PmWiki's design encourages customization with a wide selection of custom extensions, known as "recipes" available from the PmWiki Cookbook. Creating and maintaining extensions and custom installations is easy thanks to a number of well documented hooks in the wiki engine.
Prerequisites for running the PmWiki wiki engine:
PmWiki was written by the university professor and Perl 6 developer Patrick R. Michaud, who owns a trademark on the name "PmWiki". A number of other developers and users write, maintain and discuss "recipes" (special purpose configurations, add-ons, or plug-ins) in the PmWiki Cookbook and "skins" (special purpose alteration to the look and feel of pages).
The following books mention PmWiki or have dedicated chapters or sections:
PmWiki has been featured in a number of printed and online magazines including Inc Magazine, Linux Gazette, PCMag, LXer, Framasoft, Linuxfr.
The page PmWiki References lists publications about PmWiki in various languages.