StandardSetController objects allow you to create list controllers similar to, or as extensions of, the pre-built Visualforce list controllers provided by Salesforce.
Using a standard list controller is very similar to using a standard controller. First you set the
standardController attribute on the
<apex:page> component, then you set the
recordSetVar attribute on the same component.
For example, to associate a page with the standard list controller for accounts, use the following markup:
<apex:page standardController="Account" recordSetVar="accounts">
recordSetVar attribute not only indicates that the page uses a list controller, it can indicates the variable name of the record collection. This variable can be used to access data in the record collection.