25% of the web, every fourth site, is now powered by WordPress, according to W3Tech. Usability and open source in a nutshell. Nearest competitor is Joomla (under 3%), then Drupal (barely over 2%). Just over 57% of the sites have no obvious CMS at all though. That’s where the growth is, says WordPress creator Matt Mullenweg. There’s still a lot to do for open source, and democratic, online publishing.