Or to be more specific, an Entity Bean exactly maps to a record in your domain model. In a relational database context, there is one Bean for each row in a table. This is not a new concept, since this is how object databases have been modeled all along. A primary key identifies each Entity Bean. Entity beans are transactional and are recoverable following a system crash.
Entity beans are also implicitly persistent.
An EJB object can manage its own persistence, or it can delegate its persistence to its container. Entity Beans always have states which can be persisted and stored across multiple invocations. Multiple EJB Clients may however share an Entity Bean. The lifetime of an Entity Bean is not limited by the lifetime of the virtual machine within which it executes. A crash of the virtual machine may result in a rollback of the current transaction, but will neither destroy the Entity Bean nor invalidate the references that other clients have to this Entity Bean.