Information Hiding

Classes in Java (and some other OO languages) allow to specify three levels of access for attributes and methods of their objects:

Public: Free access to every client.

Protected: Access only to its implementation and the implementation of subclasses.

Private: Access only to its implementation.

Restricting access (information hiding) allows to reduce the number of potential dependencies which in turn reduces the amount of work necessary in case of changes and/or extensions.