What are the different session modes in Hibernate and how do they differ?

In Hibernate, a session (Session) is the main interface for interacting with the database, through which operations such as saving, updating, deleting, and retrieving objects are performed.

The main modes of session operation can be viewed through the lens of object state management and transactions:

1. Transient (transient state) — an object created in memory but not associated with a session and not saved in the database.

2. Persistent (persistent state) — an object associated with a session, with changes tracked and synchronized with the database upon commit.

3. Detached (detached state) — an object that was associated with a session but the session is closed or the object is detached; changes are not automatically tracked.

Additionally, sessions can operate in different transaction management modes:

• Automatic transaction management — the session opens and closes transactions itself.
• Manual transaction management — the developer explicitly manages transactions via the API.

The differences in session operation modes affect how and when object changes are saved to the database, and how Hibernate manages caching and data synchronization.