Inheritance

The language feature that is most often associated with object-oriented programming is inheritance. Inheritance is the ability to define a new class that is a modified version of a previously-defined class (including built-in classes).

The primary advantage of this feature is that you can add new functions or instance variables to an existing class without modifying the existing class. This is particularly useful for built-in classes, since you can't modify them even if you want to.

The reason inheritance is called "inheritance" is that the new class inherits all the instance variables and functions of the existing class. Extending this metaphor, the existing class is sometimes called the parent class and the new class is called the subclass.