Carlo Cayos thinks this is interesting:

Types of EJBs

Session beans are great for implementing business logic, processes, and workflow. And because enterprise applications can be complex, the Java EE platform defines several types of EJBs. A session bean may have the following traits:

• Stateless: The session bean contains no conversational state between methods, and any instance can be used for any client. It is used to handle tasks that can be concluded with a single method call.
• Stateful: The session bean contains conversational state, which must be retained across methods for a single user. It is useful for tasks that have ...