What is public, protected, private?

Public: Class members having this specifier are accessible from objects created outside the class

Protected: These members will be accessible from inside the class and its derived classes.

Private: These members will be available from inside the current class only.

Samik your explanation is nice.
Easy for the beginner to understand.

* Public variables, are variables that are visible to all classes.
* Private variables, are variables that are visible only to the class to which they belong.
* Protected variables, are variables that are visible only to the class to which they belong, and any subclasses.

Deciding when to use private, protected, or public variables is sometimes tricky. You need to think whether or not an external object (or program), actually needs direct access to the information. If you do want other objects to access internal data, but wish to control it, you would make it either private or protected, but provide functions which can manipulate the data in a controlled way.