Custom Navigation Handler in JSF

To get idea about what is custom navigation handler in JSF and how to implment that visit the below links.

http://stackoverflow.com/questions/2387191/jsf-1-2-navigationhandler-custom-navigation
http://www.jroller.com/cenkcivici/entry/custom_jsf_navigation_handler_for
http://old.nabble.com/NavigationHandler-td11946094.html