WordPress was born out of a desire for an elegant, well-architectured personal publishing system built on PHP and MySQL and licensed under the GPL. It is the official successor of b2/cafelog. WordPress is modern software, but its roots and development go back to 2001. It is a mature and stable product. We hope that by focusing on user experience and web standards we can create a tool different from anything else out there.
2001 - b2 cafelog launched by Michel Valdrighi.
2004 - Plugins are introduced with Version 1.2 (Mingus).
2007 - A new UI, autosave, spell check and other new features were introduced in Version 2.1 (Ella). Widgets, better Atom feed support, and speed optimizations came out in Version 2.2 (Getz). And tagging, update notifications, pretty URLs and a new taxonomy system were introduced in Version 2.3 (Dexter).
2008 - Version 2.5 (Brecker) was released with a new administration UI design by Happy Cog, and introduced the dashboard widget system and the shortcode API. Version 2.6 (Tyner) built on 2.5 and introduced post revisions and Press This. A usability study was done on 2.5 over the summer, leading to the development of the Crazyhorse prototype, and the eventual release of Version 2.7 (Coltrane), which redesigned the administration UI to improve usability and make the admin tool more customizable. Version 2.7 also introduced automatic upgrading, built-in plugin installation, sticky posts, comment threading/paging/replies and a new API, bulk management, and inline documentation.
2009 - Version 2.8 (Baker) introduced a built-in theme installer and an improved widget UI and API. Version 2.9 (Carmen) introduced image editing, a Trash/Undo feature, bulk plugin updating, and oEmbed support.
2010 - Version 3.0 (Thelonious) was a major release, it introduced custom post types, made custom taxonomies simpler, added custom menu management, added new API's for custom headers and custom backgrounds, introduced a new default theme called "Twenty Ten" and allowed the management of multiple sites (called MultiSite).
2011 - Version 3.1 (Gershwin) introduced post format and the admin bar. Version 3.2 (Reinhardt) made WordPress faster and lighter, this version upgraded minimum requirements to PHP 5.2.4 and MySQL 5.0.15, and introduced a new default theme called "Twenty Eleven". Version 3.3 (Sonny) made WordPress more friendly for beginners with welcome messages and feature pointers.
2013 - Version 3.6 (Peterson) introduced a new default theme called "Twenty Thirteen", builtin Audio and Video support, dynamic and scalable Revisions, improved Autosave and Post Locking. Version 3.7 (Basie) introduced automatic updates for maintenance and security updates, stronger password meter, improved search results and better global support for localized versions. Version 3.8 (Parker) introduced new admin design and new default theme called "Twenty Fourteen".
2014 - Version 3.9 (Smith) improved the media experience and introduced live widget and header previews. Version 4.0 (Benny) introduced a grid view for the media library and for installing plugins, and visual previews for embedded content. Version 4.1 (Dinah) introduced a refreshed Distraction Free Writing mode, language installation from the Settings screen, and a beautiful new default theme, "Twenty Fifteen".
2015 - Version 4.2 (Powell) added emoji support, add extended character support and switched database encoding from utf8 to utf8mb4. Version 4.3 (Billie) added builtin site icons support and introduced formatting shortcuts in the visual editor. Version 4.4 (Clifford) added responsive images, embeddable posts, and a new default theme, "Twenty Sixteen."
2016 - Version 4.5 (Coleman) added inline links, added formatting shortcuts and responsive previews in Customizer.