defaultPortlets.xml ->  Determines what portlets the user is subscribed to when 
                        they haven't authenticated or have just signed up for an 
                        account.


recommendedPortlets.xml ->  When the user is prompted to choose some portlets
                            these are recommended first.

allPortlets.xml -> Determines the portlets that the user may subscribe to.

portletMarkup.xsd -> The XML Schema that describes Portlet Markup Language