Java 2 Platform, Enterprise Edition (J2EE) is a platform for developing multi-tier enterprise applications. It was developed by Sun Microsystems, now owned by Oracle, and includes a set of services, APIs, and protocols that provide the functionality necessary for developing distributed, web-based, enterprise-scale applications.

J2EE consists of a number of technologies and APIs for enterprise services, including:

1. Java Servlets: This is a server-side technology used to extend the capabilities of a server. With servlets, we can handle form data, send cookies, and manage HTTP sessions.

2. JavaServer Pages (JSP): This is another technology that lets developers create dynamic, platform-independent web-based applications. JSPs are similar to PHP and are used to create HTML, XML, or other types of documents.

3. Enterprise JavaBeans (EJB): These are used to encapsulate the business logic of an application. They run in an EJB container and provide services such as transaction management, persistence, and security.

4. Java Message Service (JMS): This is a Java API that allows applications to create, send, receive, and read messages, enabling distributed communication that is loosely coupled, reliable, and asynchronous.

5. Java Naming and Directory Interface (JNDI): This is an API for accessing different kinds of naming and directory services so that Java software clients can discover and look up data and objects via a name.

6. Java Database Connectivity (JDBC): This API provides methods for querying and updating data in a database. JDBC provides a way to connect Java applications to a wide range of databases and data sources.

7. Java Transaction API (JTA): This is used for distributed transaction management in Java EE applications. It allows applications to perform distributed transactions, i.e., transactions that access and update data on two or more networked computer resources.