WordPress is a free and open source blogging tool and a dynamic content management system (CMS) based on PHP and MySQL. It has many features including a plug-in architecture and a template system. WordPress is used by over 14.7% of Alexa Internet's "top 1 million" websites and as of August 2011 manages 22% of all new websites. WordPress is currently the most popular CMS in use on the Internet.
It was first released on May 27, 2003, by founders Matt Mullenweg and Mike Little as a fork of b2/cafelog. As of December 2011, version 3.0 had been downloaded over 65 million times.
WordPress template hierarchy
WordPress has a web template system using a template processor.
WordPress users may install and switch between themes. Themes allow users to change the look and functionality of a WordPress website or installation without altering the informational content. Themes may be installed by using the Wordpress "Dashboard" administration tool, or by uploading theme folders via FTP. The PHP and HTML code in themes can also be edited for more advanced customizations.
One very popular feature of WordPress is its rich plugin architecture which allows users and developers to extend its abilities beyond the features that are part of the base install; WordPress has a database of over 18,000 plugins with purposes ranging from SEO to adding widgets.
Widgets are small modules that offer users drag-and-drop sidebar content placement and implementation of many plugins' extended abilities. Widgets allow WordPress developers to add functionality to their sites. These small modules can be used to add functionality such as a slideshow, Facebook-like box, small news slider, and more.
Multi-user and multi-blogging
Prior to WordPress 3.0, WordPress supported one blog per installation, although multiple concurrent copies may be run from different directories if configured to use separate database tables. WordPress Multi-User (WordPress MU, or just WPMU) was a fork of WordPress created to allow multiple blogs to exist within one installation that is able to be administered by a centralized maintainer. WordPress MU makes it possible for those with a website to host their own blogging community, as well as control and moderate all the blogs from a single dashboard. WordPress MU adds eight new data tables for each blog.
WordPress MU merged with WordPress as part of the 3.0 release.
Native applications exist for WebOS, Android, iOS (iPhone, iPod Touch, iPad), Windows Phone 7, and BlackBerry which provide access to some of the features in the WordPress Admin panel and work with WordPress.com and many WordPress.org blogs.
Other features of note
WordPress also features integrated link management; a search engine friendly, clean permalink structure; the ability to assign nested, multiple categories to articles; and support for tagging of posts and articles. Automatic filters are also included, providing standardized formatting and styling of text in articles (for example, converting regular quotes to smart quotes). WordPress also supports the Trackback and Pingback standards for displaying links to other sites that have themselves linked to a post or article.
b2/cafelog, more commonly known as simply b2 or cafelog, was the precursor to WordPress. b2/cafelog was estimated to have been employed on approximately 2,000 blogs as of May 2003. It was written in PHP for use with MySQL by Michel Valdrighi, who is now a contributing developer to WordPress. Although WordPress is the official successor, another project, b2evolution, is also in active development.
WordPress first appeared in 2003 as a joint effort between Matt Mullenweg and Mike Little to create a fork of b2. The name WordPress was suggested by Christine Selleck Tremoulet, a friend of Mullenweg.
In 2004 the licensing terms for the competing Movable Type package were changed by Six Apart and many of its most influential users migrated to WordPress. By October, 2009, the 2009 Open Source content management system Market Share Report reached the conclusion that WordPress enjoyed the greatest brand strength of any open source content management systems.
In 2007 WordPress won a Packt Open Source CMS Award.
In 2009 WordPress won the Packt best Open Source CMS Awards.
In 2010 WordPress won the Hall of Fame CMS category in the 2010 Open Source Awards.
In 2011 WordPress won the Open Source Web App of the Year Award at The Critters.
Removal of sponsored themes
On July 10, 2007, following a discussion on the WordPress ideas forum and a post by Mark Ghosh in his blog Weblog Tools Collection, Matt Mullenweg announced that the official WordPress theme directory at http://themes.wordpress.net would no longer host themes containing sponsored links. Although this move was criticized by designers and users of sponsored themes, it was applauded by WordPress users who consider such themes to be spam. The official WordPress theme directory ceased to accept any new themes, including those without sponsored links, shortly after the announcement was made. Sponsored themes are still available elsewhere, as well as free themes with additional sponsored links added by third parties.
On July 18, 2008, a new theme directory opened at http://wordpress.org/extend/themes/. It was styled along the same lines as the plug-ins directory, Any theme that is uploaded to it will be vetted, first by an automated program and then by a human.
On December 12, 2008, over 200 themes were removed from the WordPress theme directory as they did not comply with GPL License requirements. Today, author mentions are permitted in each theme but the official policy does not allow for sponsorships or links to sites distributing non-GPL compatible themes. Non-GPL compliant themes are now hosted on other theme directories.
Most WordPress releases are codenamed after well-known jazz musicians, starting after version 1.0.
||27 May 2003
||Used the same file structure as its predecessor, b2/cafelog, and continued the numbering from its last release, 0.6. Only 0.71-gold is available for download in the official WordPress Release Archive page.
||22 May 2004
||Added support of plugins; which same identification headers are used unchanged in WordPress releases .
||17 February 2005
||Added a range of vital features, such as ability to manage static pages and a template/theme system. It was also equipped with a new default template (code named Kubrick) designed by Michael Heilemann.
||31 December 2005
||Added rich editing, better administration tools, image uploading, faster posting, improved import system, fully overhauled the back end, and various improvements to plugin developers.
||22 January 2007
||Corrected security issues, redesigned interface, enhanced editing tools (including integrated spell check and auto save), and improved content management options.
||16 May 2007
||Added widget support for templates, updated Atom feed support, and speed optimizations.
||24 September 2007
||Added native tagging support, new taxonomy system for categories, and easy notification of updates, fully supports Atom 1.0, with the publishing protocol, and some much needed security fixes.
||29 March 2008
||Version 2.4 was skipped, so version 2.5 added two releases worth of new code. The administration interface was fully redesigned, and the WordPress website to match the new style.
||15 July 2008
||Added new features that made WordPress a more powerful CMS: it can now track changes to every post and page and allow easy posting from anywhere on the web.
||11 December 2008
||Administration interface redesigned fully, added automatic upgrades and installing plugins, from within the administration interface.
||10 June 2009
||Had improvements in speed, added automatic installing of themes from within administration interface, introduces the CodePress editor for syntax highlighting and a redesigned widget interface.
||19 December 2009
||Added global undo, built-in image editor, batch plugin updating, and many less visible tweaks.
||17 June 2010
||Added a new theme application programming interfaces (API); the merge of WordPress and WordPress MU, creating the new multi-site functionality, a new default theme called "Twenty Ten", and many less visible tweaks.
||23 February 2011
||Added the Admin Bar, which is displayed on all blog pages when an admin is logged in, and Post Format, best explained as a Tumblr like micro-blogging feature. It provides easy access to many critical functions, such as comments and updates. Includes internal linking abilities, a newly streamlined writing interface, and many other changes.
||4 July 2011
||Focused on making WordPress faster and lighter. Released only four months after version 3.1, reflecting the growing speed of development in the WordPress community.
||12 December 2011
||Focused on making WordPress friendlier for beginners and tablet computer users.
||13 June 2012
||Focused on improvements to theme customization, Twitter integration and several minor changes.
||5 December 2012
||Support of the Retina Display, color picker, new theme: Twenty Twelve, improved image workflow 
After the release of WordPress 3.0, the development team took a release cycle off from the WordPress software to focus on expanding and improving the WordPress community. WordPress 3.1 was subsequently released in February, 2011. With version 3.2, released on July 4, 2011, the minimum requirement PHP version and MySQL were raised as well.
Many security issues were uncovered in the software, particularly in 2007 and 2008. According to Secunia, WordPress in April 2009 had 7 unpatched security advisories (out of 32 total), with a maximum rating of "Less Critical". Secunia maintains an up-to-date list of WordPress vulnerabilities.
In January 2007, many high-profile search engine optimization (SEO) blogs, as well as many low-profile commercial blogs featuring AdSense, were targeted and attacked with a WordPress exploit. A separate vulnerability on one of the project site's web servers allowed an attacker to introduce exploitable code in the form of a back door to some downloads of WordPress 2.1.1. The 2.1.2 release addressed this issue; an advisory released at the time advised all users to upgrade immediately.
In May 2007, a study revealed that 98% of WordPress blogs being run were exploitable because they were running outdated and unsupported versions of the software.
In a June 2007 interview, Stefan Esser, the founder of the PHP Security Response Team, spoke critically of WordPress's security track record, citing problems with the application's architecture that made it unnecessarily difficult to write code that is secure from SQL injection vulnerabilities, as well as some other problems.
Individual installations of WordPress can be protected with security plugins such as Better WP Security, WP Security Scan and many others. Users can also protect their WordPress installations by taking steps such as renaming the default admin account, as well as editing the site's .htaccess file to prevent many types of SQL injection attacks and block unauthorized access to sensitive files. 
Development and support
Matt Mullenweg and Mike Little were cofounders of the project. The core contributing developers include Ryan Boren, Mark Jaquith, Matt Mullenweg, Andrew Ozz, Peter Westwood and Andrew Nacin.
WordPress is also developed by its community, including WP testers, a group of volunteers who test each release. They have early access to nightly builds, beta versions and release candidates. Errors are documented in a special mailing list, or the project's Trac tool.
Though largely developed by the community surrounding it, WordPress is closely associated with Automattic, the company founded by Matt Mullenweg. On September 9, 2010, Automattic handed the WordPress trademark to the newly-created WordPress Foundation, which is an umbrella organization supporting WordPress.org (including the software and archives for plugins and themes), bbPress and BuddyPress.
WordCamp developer and user conferences
"WordCamp" is the name given to all WordPress-related gatherings, both informal unconferences and more formal conferences. The first such event was WordCamp 2006 in August 2006 in San Francisco, which lasted one day and had over 500 attendees. The most recent event was WordCamp San Francisco in August 2011, which ran for three days and had over 1,000 attendees. The first WordCamp outside San Francisco was held in Beijing in September 2007. Since then, there have been over 150 WordCamps around the world, for an average of nearly one a week. WordCamp San Francisco, an annual event, remains the official annual conference of WordPress developers and users.
As a free and open source platform, WordPress relies on peer support. The primary support website is WordPress.org.
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