Right now WordPress is the world’s most widely used website management and content management platform. This Tech Republic link says that 27% of the web right now is powered by WordPress. In terms of CMS usage WordPress covers almost 59.4% of the total market. Everyday, 500 new websites and blogs are being created using WordPress (source), many of which use web hosting providers such as the ones that can be found at this hyperlink or other sites around the internet.
According to the above link, these famous websites are powered by WordPress:
More than 24 posts are being created every second using WordPress.
Statistics between WordPress.com and the self hosted WordPress.org often get mixed up. WordPress.com is a third-party hosted blogging platform that people use to manage blogs without having their own domain. WordPress.org on the other hand allows you to download the WordPress installation files and set up the entire platform under your own domain.