The J2EE platform consists of a multitier application architecture, based on Model View Controller methodology. Varieties of application component models are available for each of these tiers, by which all kinds of enterprise applications can be built.
These application components are serviced by a rich set of drivers and utilities. They take care of all essential services that might be required by the applications (for example, database connectivity, e-mailing, authentication, and distributed directory access.
Application components can be hosted in J2EE runtime environments called containers.
For a high-level overview of J2EE, please read my earlier article "J2EE - What It Is and What It's Not." To explore the constituants of J2EE, please read my next article "J2EE Components and APIs."