THIS IS A BETA VERSION - Currently in development - Create and Manage Cronjobs in WP by loading Scripts via URLs, including Scripts, running Functions
What does wp_cron() do?
As you receive visitors on your site, WordPress checks your database to see if anything is scheduled to run. If you have a wp_cron() job scheduled every 12 hours, then the very first visitor 12+ hours from the last scheduled run of that function will trigger the function to run in the background. The Cronjob (or Cron Job) sends a request to run cron through HTTP request that doesn't halt page loading for the visitor.
How is wp_cron() different from Server configured Cronjobs?
Cronjobs configured on a server run on their intervals automatically, while wp_cron() jobs run only after being triggered from a visitor to your site.