Magento events and observers are a good old way of extending Magento. They came from Magento 1, but an approach is well-known beyond the Magento community and platform. It follows an observer design pattern and has different implementation and variations in different frameworks. This article covers how Event Framework was implemented in Magento and how it’s suggested to be using by Magento Development Team.
Observers are very powerful instrument in Magento. They allow us to bind our functionality to some Magento events. Many of you know about dispatchEvent function. This function calls all observers registered for this event. For example, we have the following code snippet placed in this app/code/core/Mage/Catalog/Model/Resource/Product/Collection.php file.