What is crontab and explain its functionality and explain the format of crontab

Cron is a scheduler that executes the commands at a regular interval as per the specific date and time defined. We have multiple users in Linux, and all the users can have their crontab separately. The crontabs files are saved at a particular location that is /var/spool/cron/crontabs.
There are six fields in the format for the crontab that is as below:
<Minute><Hour><Day_of_the_Month><Month_of_the_Year><Day_of_the_Week><command/program to execute>