WordPress is a free and open-source content management system (CMS) based on PHP and MySQL (distributed under the GNU General Public License) and is among the most popular content management systems in the world. Known for its famous 5-minute installation, WordPress ships as a very lightweight, easy to use system that can be further extended via plugins (equivalent to Drupal modules or Joomla extensions).
WordPress has a large, mature ecosystem with extensive support and documentation readily available, as well as a range of plugins and themes (some free, some paid) that can enhance the core CMS and add more functionality to the system.
WordPress was the third CMS with which CiviCRM integrated (2012) and continues to see growth in its adoption as a platform to use CiviCRM. Because of this, there is an increasing number of CiviCRM extensions built to extend WordPress’ functionality.
If you’re new to the CMS market, WordPress could be a great starting to both web publishing and to CiviCRM.