Index J2EE TM Developer's Guide Entity Beans Characteristics of Entity Beans Entity beans differ from session beans in several ways.
Entity beans are persistent, allow shared access, and have primary keys.
Because the state of an entity bean is saved in a storage mechanism, it is persistent. Persistence means that the entity bean exists beyond the lifetime of the application or the J2EE server process. If you've worked with databases, you're familiar with persistent data. The data in a database is persistent because it still exists even after you shut down the database server or the applications it services. You declare the persistence type with the Application Deployment Tool, which stores the information in the entity bean's deployment descriptor.