WordPress is a CMS or content management system. It was originally written as software to help bloggers focus on their writing, but it has expanded well beyond that original role. WordPress now powers around 25% of the Internet. That means that literally billions of sites depend on WordPress to manage their content, and they aren't all blogs. In fact, about half of the top ten thousand sites in the world use WordPress.
So many people are choosing WordPress because it is simple to use and install. It is also quite powerful. It comes with a robut plugin and theme repository, which allows users to add functionality and design with just a few clicks. Most plugins and themes are free too.
I am a Chicago based WordPress developer. I can build custom WordPress adminstration panels, multisite-installations, plugins and themes. WordPress is written in PHP and uses databases. As a PHP developer, I can optimize existing WordPress themes to yield better performance. I can also add functionality to themes, such as by making them responsive to screen size or adding other features.