WordPress is an open-source content management system (CMS) that allows publishing and managing content on websites without requiring technical expertise. It is highly customizable through the use of themes and plugins and powers over 40% of websites globally, including high-profile sites like Sony, Mercedes Benz, and The New Yorker. While WordPress is generally secure, sites can be compromised if outdated software, plugins, or themes are used or if login credentials are weak. Maintaining security requires keeping all components updated, using strong unique passwords, and following best practices.