URLFOR() Directing to a Visualforce page:

In addition to invoking actions, you can also use the URLFOR() function for simple navigation
to redirect a user to any web page, including any Visualforce page, by specifying the target as the
name of your page prepended with apex/ to create the partial URL.

For example, to redirect to our Visualforce page named CustomAccountPage we would use the
following syntax:

<apex:outputLink value=”{!URLFOR(‘apex/CustomAccountPage’)}” >
 Goto My Custom Account Page
</apex:outputLink>

In addition, you can also construct links referencing any Frontdoor URL pattern to directly launch
an insert, edit or view action on any sObject by simple URL navigation.

<apex:outputLink value=”{!URLFOR(‘/’+Contact.accountId)}” >
 View My Parent Account
</apex:outputLink>