Cron is a widely used tool which is used to schedule tasks or so-called jobs on any Unix-like operating system. It can be set up to run the corn jobs daily, weekly, or monthly, but it can also be set up to run any given period or once only.
For example, you want to run a backup script during off-work hours. Using cron jobs, you can easily schedule the script to run at a specific time daily, every second day, weekly, or any other period.