Enterprise JavaBeans (EJB) is a server-side component architecture for the Java Platform, Enterprise Edition (Java EE). EJB technology enables rapid and simplified development of distributed, transactional, secure and portable applications based on Java technology.

The EJB architecture addresses the development of enterprise-level applications, providing a framework for developing and executing distributed business applications. Distributed applications allow the data and processing tasks to be split across many different computers, connected via a network.

There are three types of Enterprise JavaBeans:

1. Session Beans: These are the most common EJB and they represent a workflow on behalf of a client. They can be stateful (maintaining state across methods and transactions) or stateless (not maintaining any state).

2. Message-Driven Beans (MDB): These are EJB that are designed to process Java Messaging Service (JMS) messages asynchronously.

3. Entity Beans: These represented shared data persistency. However, since Java EE 6, the use of Entity Beans is considered deprecated and the Java Persistence API (JPA) is recommended instead for ORM (Object-Relational Mapping).

Some of the major advantages of using EJBs include:

• Transaction Management: The EJB container provides a runtime environment that automates many aspects of transaction and state management.

• Security: EJBs can be configured to include declarative access control rules.

• Remote Method Invocation (RMI): EJB supports remote method invocation, making it easy to create distributed applications.

• Aspect Oriented Programming (AOP): You can plug in cross-cutting concerns such as logging, auditing, or security checks.