Packaging data with the functions that can operate on that data in well-named classes.

Providing clearly named and well-documented public functions that enable users of the class to do whatever needs to be done with objects of this class.

Hiding implementation details.

The set of public function prototypes in a class is called its public interface.

The set of non-public class members, together with the member function definitions, is called its implementation.

Encapsulation permits the programmer to use a consistent naming scheme for the members of classes.

There is no danger of ambiguity if the same member name is also used in another class elsewhere in the program.

Examples: m_unitCost and toString()