WordPress, released in 2003, is a free and open-source content management system based on PHP and MySQL. It comes with a plugin architecture and a template system, but needs to be installed on a web server to function. As of 2018, WordPress is used by more than 29.4% of the top 10 million websites and supports more than 60 million websites, making it the most popular website management or blogging system on the internet. In Stack Overflow’s 2018 Developer Survey, 16.1% of developers have worked with WordPress in the last year. The average hourly rate for WordPress developers is about $61-80. Also consider looking at PHP developer hourly rates.