Java 2 Enterprise Edition

J2EE (Java 2 Enterprise Edition) is the latest suite of API's for the enterprise from Sun Microsystems.  What is in the suite?  EJB, Servlets, JSP, JDBC, JNDI, RMI/IIOP, JTA/JTS, JMS, and JavaMail. Here is what all of these acronyms stand for:

EJB - Enterprise JavaBeans

A component model for the server or middle tier. Enterprise Beans are often confused with JavaBeans which are typically client-side reusable software components that often encapsulate visual user controls or other graphic user interface (GUI) features. Enterprise Beans are always on the server and encapsulate business logic, never GUI functionality.

Servlets

An alternative to CGI. Servlets allow the web server to take requests and direct them straight to the Java Virtual Machine running a server-side application. While CGI is a gateway from the web server to other programs on the same computer that execute in a new process, servlets are much more efficient and can reuse objects in memory an launch threads for each request instead of a whole separate process per request.

JSP - Java Server Pages

Similar to Active Server Pages (ASP), but with the power of embedded Java. Java Server Pages are actually uncompiled servlets. HTML with special server directive tags in the form <% code %> are compiled into a Java classes on the fly by the server and loaded in the JVM on the server as servlets, basically a quick and dirty servlet.

JDBC - Java DataBase Connectivity

A standard API for Java programmers to interface with any database. JDBC has been a core package in Java since 1.1 (java.sql), but J2EE includes JDBC 2.0 Standard Extension (javax.sql).

JNDI - Java Naming and Directory Interface

A uniform connection to the enterprise directory, however it happens to be implemented: Netscape LDAP, Sun NIS+, Novell Directory Service (NDS), and potentially Microsoft Active Directory.

RMI/IIOP - Remote Method Invocation

RMI over Internet Inter-Orb Protocol is a CORBA compliant distributed object interface co-developed by IBM and Sun. The best of RMI and the best of CORBA. Using RMI-IIOP, objects can be passed both by reference and by value over IIOP to another computer. Read more about RMI/IIOP at java.sun.com.

JTA/JTS - Java Transaction API and Service

A transaction manager and API for RMI/IIOP connections to allow robust transaction features such as rollbacks. The EJB component developer can state transaction characteristics at design time or even at deployment time using declarative statements. The JTS (transaction manager) built into the application server is then responsible for all of the details involved in the transaction management.

JMS - Java Messaging Service

A reliable, flexible service for the asynchronous exchange of critical business data and events.

JavaMail

A set of classes that model a mail system including implementations of the IMAP and SMTP service providers.  JavaMail provides developers with a protocol independent framework for building mail and messaging applications.