Top 10 Most Popular Drupal Modules
Modules are like Lego building blocks. They fit together perfectly by following a predefined set of guidelines, and with a combination of modules, you can build rich and complex solutions.
There are two general categories of Drupal modules — core and contributed. Core modules are those that are shipped with Drupal and include modules such as polls, menus, taxonomy, search, feed aggregator, and forums. Contributed modules are all of the modules created by the community that extend and enhance the functional footprint of Drupal core.