Automation. Lets you schedule commands periodically or a future date and so on.

Crontabs take 6 arguments.

Let's use the example of backing up files. You may wish to backup "cmnatic"'s  "Documents" every 12 hours. We would use the following formatting:

0 *12 * * * cp -R /home/cmnatic/Documents /var/backups/

Useful Crontab Generator - https://crontab-generator.org/

crontab -l to see current crontabs

crontab -e to edit contabs. use man cron / man crontab for more info.