Question

I’m an extremely novice programmer who finds himself tasked with learning how to program for Magento. So please forgive me for such a rudimentary question but there don’t seem to be a ton of beginning level content on Google regarding Mage.

Can someone explain to me what exactly an observer is? What does it do? What can it be used for?

If someone can give me a super 101 explanation (not assuming much prior knowledge) you’ll be my new hero. Thanks.

Answer 1

You can consider Event observer as a trigger.
Once you have set an event observer, for example you can set observer before or after an event, i.e., You can add a event which would execute right after user adds a product to cart or before the add product to cart.

In this event observer, you can write code to customize the data which is either passed to the occuring event (before) or is the output of occured event (after)

Reference : http://www.magentocommerce.com/wiki/5_-_modules_and_development/0_-_module_development_in_magento/customizing_magento_using_event-observer_method

Event :

In Magento you may consider a Controller Action as an event, for example addAction in CartController is an event.

Observer :

As mentioned in name, the observer observes when this action occurs (in our case addAction in CartController) and calls a function either before or after this addAction is called.
You may add your custom code in this obeserver for customization.