The life cycle of entity objects consists of four states: New, Managed, Removed and Detached.
When an entity object is initially created its state is New. In this state the object is not yet associated with an EntityManager and has no representation in the database.
An entity object becomes Managed when it is persisted to the database via an EntityManager's persist method, which must be invoked within an active transaction.
A managed entity object can also be retrieved from the database and moved to removed, by using the EntityManager's remove method within an active transaction.
Detached represents entity objects that have been disconnected from the EntityManager.