In technical terms, WordPress is a free and open source blogging tool and CMS (content management system) that is powered by the PHP Web programming language and MySQL database. In layman’s terms, WordPress is a Web platform that gives you tons of features and functionality without requiring a high level of expertise in Web programming after the site is developed. There are three major parts to a WordPress installation, other than the basic WordPress code itself: themes, plugins, and widgets.
I have worked with WordPress, Weebly and SquareSpace, but mostly with WordPress because I didn’t like some of the limitations placed on me by the other two platforms. Oh, they are very good platforms however I didn’t find SquareSpace’s drag and drop interface to be all that intuitive in particular (Weebly does a much better job).