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plugin-developer-learning-pathway/12-Cron/01-Introduction-to-WP-Cron.md

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+# Introduction to WP Cron
+
+On some occasions, we need to have some actions that need to be executed periodically instead of executing when a user has an interaction.
+
+A good example of this would be a subscription.
+
+First, we would need some logic to proceed with the registration from the customer to the subscription with some usual logic.
+
+Then we would have to bill the user monthly, and for this part of the logic we would need a Cron. This is due to the fact we don't want the customer to pay manually each month, but instead we want the payment to proceed automatically.
+
+## Understanding how Cron works
+
+A Cron is always based on two parts:
+- A recurrence that will define the time when the Cron are executed.
+- A task that will be executed when the Cron is fired.
+
+## WP Cron 
+
+Real crons needs to be settled up by the WordPress user to be able to run, which is not something straightforward nor an easy process.
+
+That is why WordPress introduced WP Crons, they are emulated crons that run by default on a WordPress website when real crons are not configured.
+
+That way, users are not left with a broken website if they forgot to set up the crons.
+
+However, WP Cron also have their own drawbacks compared to crons.
+
+They rely on a user to load the page to run, and so they can be unreliable if you have little traffic on your website.
+
+## Switching from WP Cron to Cron
+
+At the level of the plugin, it is not possible to know of we are using WP Crons or Crons as it will be handled inside WordPress configuration.
+
+This, even if it can seem like a problem, is in fact good news for us plugin developers.
+This due to the fact there will be one syntax to register Crons and WordPress will handle us which one from WP Crons or Crons will be used.