crontab is the utility in Unix-style operating systems that is used to maintain automated tasks. The task schedule is stored in a text file known as a 'cron file' or 'crontab file'; each user can have their own cron file. A background process (daemon) runs every minute to check for cron events intended to start. Events can be set up to run every minute, hour, day, or other combinations of times. Cron files are usually found under the /etc/ directory with names including 'cron'.
The crontab file has one event per line, with fields separated by the space character.