WordPress is an open source blog publishing application powered by PHP and MySQL. It allows for content management and has a plugin architecture and templating system. Key features include widgets, themes, integrated link management, tagging, trackbacks, and plugins for sidebar widgets. Terms used include posts, tags, categories, media library, links, pages, dashboards, widgets, plugins, archives, and RSS feeds. Advantages are that it is free, fast to set up, easy to learn and customize, and has a large community developing add-ons. Disadvantages include similar looking themes and potential security and performance issues.