You can call Drupal a Content Management System (CMS), Content Management Framework (CMF) or a Web Application Framework (WAF). With its modular and flexible architecture, Drupal can be used to build a simple blog to a complex multisite social networking application. Drupal Core is what you need to start building a site with Drupal. It is a collection of common functions for Content Management, User Management, Content Syndication ……… Read more to Know Drupal