One of Magento's core features is the ability to handle multiple websites and stores with a single Magento installation. Internally, Magento refers to each of these instances as scopes.
Values for certain elements such as products, categories, attributes, and configuration are scope-specific and can differ on different scopes. This gives Magento tremendous flexibility. For example, a product can be set up on two different websites with different prices but still share the rest of the attribute configuration.
As developers, one of the areas where we will be using scopes the most is when working with configuration. The different configuration scopes available in Magento are as follows:
Global: As the name implies, this applies across all scopes.
Website: These are defined by a domain name and are composed by one or more stores. Websites can be set up to share customer data or be completely isolated.
Store: These are used to manage products and categories and to group store views. Stores also have a root category that allows us to have separated catalogs per store.
Store view: By using store views, we can set up multiple languages on our store frontend.
Configuration options in Magento can store values on three scopes (global, website, and store views). By default, all the values are set on the global scope. Using system.xml on our modules, we can specify the scopes on which the configuration options can be set. Let's revisit our previous system.xml file:
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<field_name translate="label comment">
<label>Enabled</label>
<comment>
<![CDATA[Comments can contain <strong>HTML</strong>]]>
</comment>
<frontend_type>select</frontend_type>
<source_model>adminhtml/system_config_source_yesno</source_model>
<sort_order>10</sort_order>
<show_in_default>1</show_in_default>
<show_in_website>1</show_in_website>
<show_in_store>1</show_in_store>
</field_name>
…