One of the most common questions we get from new Drupal users is, "Which modules do people normally use?"
That's a big question, with over 20,000 modules, but some are far more popular than others.
Webchick, one of the Drupal core developers, has used the statistics available on Drupal.org to make a list of the most popular Drupal 7 modules. This is different from the public stats on Drupal.org module pages which show the popularity of modules across all versions.
Here's an introduction to the 20 most popular Drupal 7 modules: