Cron is a system which was originally built for UNIX that enables users to execute commands, programs and other actions at specified times. As Wikipedia so eloquently puts it, “Cron is a time-based job scheduler.”

Basically, what that means is you can schedule a task to take place at a specific time, without having to manually execute any code at that time by setting up a cron job. But how does this relate to your WordPress website? Setting up your WordPress website to use the UNIX cron system built into your server’s operating system is possible; however, it can be problematic for two main reasons:

1. Your web host might not permit you to set up cron for security reasons.
2. Different servers might require cron to be set up in different ways, which would require familiarity with a wide variety of systems.
If the WordPress team couldn’t rely on using each server’s cron, then how did they schedule tasks to be performed? They built WordPress Cron.

Read full post at: https://www.todhost.com/knowledgebase/771/How-to-Disable-WordPress-Cron-and-Replace-it-with-a-Real-Cron-Job.html