At the surface, all seem to work. Are there any less obvious implications/consequences of choosing one over the other?

2 Answers 2


Magento has three "areas" by default: frontend, adminhtml and install, which are used to separate several things like translations and designs.

The area is loaded and set once when Magento is initialized, see Mage_Core_Model_App_Area::load() for details. You will notice an additional area admin, but it seems like this is not used (anywhere anymore?). Some modules might add new areas, for example test by EcomDev_PHPUnit.

Observers are also defined per area, but additionally you can define then in <global> so that they apply in all areas.

Only observers defined in the current area and in global will be executed. Global observers always come first.

Defining an observer in <default> or <admin> actually should not work at all.

  • Thanks for your answer. You wrote "install" area. Did you mean "global" area (Mage_Core_Model_App_Area::AREA_GLOBAL) ?
    – fris
    Jul 9, 2015 at 21:02
  • 1
    No, I meant install - it is used during the Magento installation wizard. Take a look at Mage_Install_Controller_Action (actually this one seems to be only used for the theme, so you cannot create observers specifically for install) Jul 9, 2015 at 21:07

If you call observer between <frontend></frontend> then that observer event will only be executed on the frontend.if you write between <adminhtml></adminhtml> it will only be executed in the backend and if you write between <global></global> then the observer event will work on both frontend and backend.

for example take one event called "core_block_abstract_prepare_layout_after"

Case 1:-


Observer event "<core_block_abstract_prepare_layout_after>" will only work in the backend

Case 2:-


Observer event "<core_block_abstract_prepare_layout_after>" will only work in the frontend

Case 3:-


Observer event "<core_block_abstract_prepare_layout_after>" will only work in the frontend and backend

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