A cron job is an automated task, which performs a particular action - usually executing a script in the hosting account. The task is scheduled, therefore it will run regularly - weekly, daily, hourly and so on. There are various reasons to employ a cron job for your websites. For instance, you may get day-to-day reports how many visitors have signed up on your site, a temp folder may be emptied automatically weekly or a backup copy of your content may be generated in a separate folder in your web hosting account. Using cron jobs can help you with the management of your sites as you're able to have numerous things completed automatically and have reports for them, in lieu of spending precious time and efforts to do them manually.