Typically you’ve one module in your Zend App – the default one. In the basic installation of the framework, you put all the controllers, models and views directly in the application folder, as described below.

/application
	- /controllers
		- /IndexController.php
	- /models
		- /MyModel.php
	- /views
		- /scripts
			- /index/index.phtml
/library
	- /Zend
/public_html
	- /images
	- /scripts

Bigger Apps – More Code

When the application becomes bigger and bigger the controller, models and views/scripts directories contain more and more files. That’s a bit odd, because it becomes difficult to maintain, and than the modules come in hand.

Modules in a Zend App

When it comes to setting up modular Zend App there are tons of articles in the web, but let me show you a simple directory layout and … sample code that sets up the framework.

/application
	- /modules
		+ /admin
			- /controllers
				- /IndexController.php
			- /views
				- /scripts
					- /index/index.phtml
		+ /default
			- /controllers
				- /IndexController.php
			- /views
				- /scripts
					- /index/index.phtml
	- /models
/library
	- /Zend
/public_html
	- /images
	- /scripts

Source

Simply add this into the bootstrap:

$frontController->addModuleDirectory(APPLICATION_PATH . '/modules');