The document discusses WordPress theme development. It defines what a WordPress theme is and explains that themes are made up of files like HTML, PHP, CSS and images that style a site without changing the core WordPress software. It outlines three methods for developing themes: from scratch, customizing existing themes, and building a child theme. Key files needed for basic theme development are also listed like style.css, index.php, header.php and footer.php. The document provides an overview of the template hierarchy in WordPress and explains how to create custom page templates and define a theme's description in the style.css file.