This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
Deployement descripotors define the runtime environment for your application. For example an EJB deployement descriptor defines, the JNDI names, the resource refeneces, the environment entries used by application , etc