A lot of features depend on Drupal Core's cron to function properly. Drupal defaults to running Cron every 3 hours. During development, you may want to test a feature more quickly, and choose to run Cron manually. You can do this from the "Cron" page at admin/config/system/cron, or you can do it from Drush.
The command couldn't be simpler. Just type "drush cron" and within seconds, you'll get a notice that cron was run successfully. This can make developing site significantly less time consuming.