Cron is a standard Linux command that allows you to schedule tasks to be executed sometime in the future or in some interval.
This is normally used to schedule a job that is executed in some interval -for example, to send out a mail every morning.
There are various ways to schedule the corn to run. Typically, you create a shell script to run as a Cron Job. It runs a list of commands while checking for errors and valid return codes. We can write shell script to run corn but in cpanel we can also find corn setup area where we have to just mention the time intervals. basically we can find the corn tab in advance section of the cpanel
A typical example of corn to run every 12 hour
* */12 * * * php -q /home/folder/public_html/folder/corn.php