J2EE (Java 2 Platform, Enterprise Edition) is a Java platform designed for the mainframe-scale computing typical of large enterprises.
Definition of J2EE
J2EE applications are made up of components such as JavaServer Pages (JSP), Java servlets, and Enterprise JavaBeans (EJB) modules. These components enable software developers to build large-scale, distributed applications. Developers package J2EE applications in Java Archive (JAR) files (similar to zip files), which can be distributed to production sites.
What does J2EE consist of?
J2EE is comprised of a large number of APIs that can be used to build enterprise applications. However, you don't have to use all of them in order to build J2EE applications. Here's the full list of technologies that make up J2EE:
JavaServer Pages (JSP)
Enterprise JavaBeans (EJB)
Java Message Service (JMS)
Java Naming and Directory Interface (JNDI)
Java Database Connectivity (JDBC)
Java Transaction Service (JTS)
Java Transaction API (JTA)
J2EE Connector Architecture (J2EE-CA, or JCA)