Themes 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 information content or structure of the site. Themes may be installed using the WordPress "Appearance" administration tool or theme folders may be uploaded via FTP. The PHP, HTML & CSS code found in themes can be added or edited for providing advanced features. Thousands of WordPress themes exist, some free, and some premium (paid for) templates. Plugins One very popular feature of WordPress is its plugin architecture which allows users and developers to extend its abilities beyond the core installation. WordPress has a database of over 26,000 plugins, each of which offers custom functions and features enabling users to tailor their sites to their specific needs. These customizations range SEO (Search Engine Optimization) enhancers to content displaying features, such as the addition of widgets and navigation bars. 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 WPMU) was a fork of WordPress created to allow multiple blogs to exist within one installation but is able to be administered by a centralized maintainer. WordPress MU makes it possible for those with websites to host their own blogging communities, as well as control and moderate all the blogs from a single dashboard. WordPress MU adds eight new data tables for each blog. As of the release of WordPress 3.0, WordPress MU has merged with WordPress. Mobiles Native applications exist for WebOS, Android, iOS (iPhone, iPod Touch, iPad), Windows Phone, and BlackBerry. These applications, designed by Automattic allow a limited set of options, which include adding new blog posts and pages, commenting, moderating comments, replying to comments in addition to the ability to view the stats. Other features 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. History 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. Christine Selleck Tremoulet, a friend of Mullenweg, suggested the name WordPress. 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. Awards 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.