> i am developng a web application which will
> authenticate user by username & password which type
> of authentication i should use & where i will find
> more about this
Nice to place to start with basics of web security.
http://www.javaworld.net/javaworld/jw-04-2000/jw-0428-websecurity.html
Also have look over JAAS
http://java.sun.com/security/jaas/faq.html
Finally you can decide which ever suits your needs.