EJB stands for Enterprise Java Beans, which is a specification provided by Sun Microsystems to develop secured, robust, and scalable distributed applications. EJB is a server-side software component that encapsulates the business logic of an application. It is one of several Java APIs for modular construction of enterprise software. EJB provides a standard way to implement the server-side business software typically found in enterprise applications. EJB applications are deployed on the server, so they are called server-side components. EJB is like COM (Component Object Model) provided by Microsoft, but it is different from Java Bean, RMI, and Web Services. EJB is based on distributed objects, which refers to software pieces running on multiple machines linked by a network. EJB is used to manage common concerns such as endurance, transactional probity, and security in a standard way that leaves programmers free to focus on the particular parts of the enterprise software at hand. EJB applications support load balancing, clustering, and fail-over. There are three types of enterprise beans in Java: session bean, message-driven bean, and entity bean. The EJB architecture consists of three main components: enterprise beans (EJBs), the EJB container, and the Java application server. EJBs run inside an EJB container, and the EJB container runs inside a Java application server.