Java How do you use the preference API? Where do these variables store?

Say I have the following code using the Preferences class.

Preferences prefs = Preferences.userRoot().node(this.getClass().getName());

String ID1 = "Test1";

System.out.println(prefs.getBoolean(ID1, true));

prefs.putBoolean(ID1, false);

//prefs.remove(ID1);

1. Is this variable persistent the next time I execute my program?
2. Where do these variables store?
3. What is the proper way of utilizing this?
4. Is the approach better than using properties files?