This document provides an overview of popular modules for the content management system Drupal, focusing on modules useful for libraries. It discusses modules for administration, content management, performance, navigation, user management, and library-specific functions. Popular modules are highlighted for tasks like custom fields, views, panels, web forms, images, editors, spam prevention, taxonomy, scheduling, groups, analytics, events, authentication, searching catalogs and databases. Resources for learning Drupal like books, tutorials, communities and publications are also listed.