Cron is a software utility that schedules jobs to be run, or automates tasks in the background.
Each job can be scheduled to run periodically (at specific intervals ranging from once every minute to once every year).
The cron utility is a great asset on a server that runs 24/7, when used to perform scheduled maintenance, etc.
On a PC, the cron utility can also be useful, but I personally think that it’s pranking potential is unparalleled.