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Apart from the powerful OOP way of customizing Magento which is overriding methods by subclassing Magento’s core Blocks and Models, there is another way to plug in customizations in key flow areas of your Magento eCommerce shop. Referred to as the Event-Observer methodology, Magento has been programmed to raise events in crucial areas of the flow and handling these events for customizations would keep upgradation a simple task that does not require fiddling around with Magento’s core source code. An example would be the event ‘catalog_product_save_after’ which will be raised by Magento immediately after a product is saved.