A Cron Job allows you to schedule a command to run at a specific time. They can allow you to automate repetitive tasks or to schedule a task to occur when you are unable to complete it. Cron Jobs are very flexible as they allow you to automate any command that you can run.
For example: If you have a script that outputs all new signups for an event you are holding, you may wish to have that output emailed to you once a day or once a week. This script may be called eventattend.cgi and it may be located at /home/user/scripts/eventattend.cgi To get the output mailed to you daily, add a cron job to execute /home/user/scripts/eventattend.cgi every day at a specified time, and be sure to specify the email address that the output should be sent to.