What is crontab?

Crontab (CRON TABle) is a file which contains the schedule of cron entries to be run and at specified times. File location varies by operating systems, See Crontab file location at the end of this document.

What is a cron job or cron schedule?

Cron job or cron schedule is a specific set of execution instructions specifing day, time and command to execute. crontab can have multiple execution statments.