What is WordPress?
WordPress is an open source blog publishing application powered by PHP and MySQL which can also be used for content management. It has many features including a plug-in architecture and a template system. Used by over 12% of the 1,000,000 biggest websites, WordPress is the most popular CMS in use today. For more info follow this link: en.wikipedia.org/wiki/WordPress
Below is a little video about the newest version, WordPress 4.6