# Preface Drupal is a content management system used to build websites for small businesses, e-commerce, enterprise systems, and many more. Created by over 121,000 contributors and more than 1.39 million members, Drupal 9 provides many new features for Drupal. Whether you are new to Drupal, or an experienced Drupalist, this Learning Path course takes you through the journey of building, extending, and customizing websites to build highly scalable and enterprise-ready websites. Drupal is a free and open source CMS written in PHP and distributed under the GNU General Public License. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://drupal-book.andy.da.md/preface.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.