cron can be used to schedule timed event execution of binaries and scripts, e.g. download of EPG guides on a repeating time interval (hourly, every 12 hours, etc.) or running a nightly backup script in the background at 2am.
Running crontab -e will open the root user crontab in nano allowing you to paste content your cron commands. Use ctrl+o to save the file and ctrl-x to exit nano.
For more info on cron commands, see: https://help.ubuntu.com/community/CronHowto