The cron feature in Drupal is an important Drupal feature that you should really get to know.

What Is Cron?

Cron is a php script that activates features that need to be run on a periodic basis. If you look at the files for the core install of Drupal you will notice a file called cron.php. That is the file you execute when you run cron.

Why You Should Use Cron

Cron allows you to take advantage of some other important Drupal features and modules. The core search module uses cron to to index the terms included in content nodes so that they will show up in the search results when users search for them. The automatic module and theme update notifications in Drupal 6 use cron to check drupal.org for updates. The core news aggregator uses cron to check for updated news feeds. Other contributed modules use cron as well.