Event

Event library provides supports for Magento events.

Event manager is responsible for event configuration processing and event dispatching. All client code that dispatches events must ask for \Magento\Framework\Event\Manager in constructor.
Event config provides interface to retrieve related observers configuration by specified event name.
Event observer object passes data from the code that fires the event to the observer function. There are two special types of observer objects supported in this library: Cron, and Regex. Each one has its own unique functionality in addition to basic observer functionality.