What is the definition of Backing Store?

I see this term Backing Store thrown around here and there. Could someone explain the concept behind it? I first began wondering about this when I caught this term being used in the Preferences API docs.
Thanks

It's whatever persistence mechanism is actually responsible for storing/retrieving data. For J2EE EntityBeans, as an example, the "backing store" is the combination of the application server's caching mechanism and the database (typically) that the EntityBean represents. For a Map object, it's the underlying memory mechanism.
Since I've only recently become aware of the Preferences APIs, I'm supposing the backing store would be something like a Properties file, the Windows "registry," LDAP, or someother long-term (non-memory) storage mechanism.

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