Here I have delved into the J2EE architecture, explaining the characteristic of an Enterprise Application, Different Enterprise Application Models such as 2-tier architecture, 3-tier architecture & n-tier architecture. I have discussed in detail about J2EE Architecture Overview, benefits of J2EE, the J2EE Platform Technologies such as Component Technologies, Service Technologies & Communication Technologies. I have also discussed t J2EE Packaging and Deployment Descriptor.