Polymorphism is not new to C++

For many years some programming languages (such as C) have interpreted the plus operator:

• To be an arithmetic operator when applied to numeric data, and
• To be a concatenation operator when applied to string or character data.

However, in C, you could not invent polymorphic behavior that was not intrinsic to the language.

C++ allows you to customize and extend polymorphic behavior into areas not supported as an intrinsic capability of the compiler.