If you writing J2EE applications, you need to deploy your application to J2EE container like JBOSS. I will shed some light on how to write simple deployment descriptors for your web applications.
I am deploying my JSP application on JBOSS. For JBOSS, we need to put our application in WAR format in deploy folder. So deployment descriptor will have following 2 tasks: Archieve the application into WARCopy that WAR to deploy folder of JBOSS