J2EE, formally Java(TM) 2 Platform, Enterprise Edition.

J2EE is a standard for "enterprise application" production, consisting of components, libraries, services, and deployment tools. The whole beast is heavily based on J2SE (of course), servlets, EJB, JSP, and XML. At least. See Sun's overview for more information.

J2EE's major competitor may turn out to be Microsoft's .NET.