Magento has a neat publish-subscribe pattern implementation that we call events and observers. By dispatching events when certain actions are triggered, we can run our custom code in response to the triggered event. The events are dispatched using the Magento\Framework\Event\Manager class, which implements Magento\Framework\Event\ManagerInterface.
To dispatch an event, we simply call the dispatch method of the event manager instance, providing it with the name of the event we are dispatching with an optional array of data we wish to pass on to the observers, as per the following example taken from the <MAGENTO_DIR>/module-customer/Controller/Account/CreatePost.php file:
$this->_eventManager->dispatch( 'customer_register_success', ...
