How does WordPress WP-Cron work and what is its fundamental limitation compared to system cron?

Question

WordPress Fundamental — Hard

How does WordPress WP-Cron work and what is its fundamental limitation compared to system cron?

Accepted Answer

WP-Cron is a pseudo-cron that only triggers scheduled tasks when a page is visited on the site. This means that if there is no traffic to the site, the tasks will not run. In contrast, system cron runs tasks at specific times regardless of site traffic.