Cron is a software utility time-based job scheduler in Unix-like computer operating system. It is used to scheduling jobs (commands or shell scripts) that run periodically at fixed times, dates, or intervals for setting up and maintaining software environments. The system maintenance or administration can be automated though its general-purpose nature which is used for downloading files and emails at regular intervals.
It’s started automatically from /etc/init.d or system on entering multi-user run levels.
You can simply use any one of the following commands to check whether cron is running or not,
# pgrep crond
# service crond status