Wordpress

Wordpress is a wonderful program that helps you easily create and manage a blog-style website. It's open-source, based on PHP and is a content management system.

It has 2 websites, wordpress.com and wordpress.org. The com website is for actually getting Wordpress, and then the org website is for downloading themes, plugins and other additions for your Wordpress.

There are a LOT of websites that use Wordpress- as of January 2015 it's used by 23.3% of the top 10 million websites. In fact, it is used by well known websites such as Target, Glad, CNN, People and even Star Wars!

Something to note is that Wordpress is not the only content management system that websites use. Alternatives include things like PHPWiki, or Enonic.







Sources:
https://wordpress.org/hosting/
http://w3techs.com/technologies/overview/content_management/all/