Abstraction
Abstraction can have a very general meaning in various fields of science and engineering. But in programming, and especially in OOP, abstraction essentially deals with abstract data types. In class-based object orientation, abstract data types are the same as abstract classes. Abstract classes are special classes that we cannot create an object from; they are not ready or complete enough to be used for object creation. So, why do we need to have such classes or data types? This is because when we work with abstract and general data types, we avoid creating strong dependencies between various parts of code.
As an example, we can have the following relationships between the Human and Apple classes:
An object of the Human class eats an object of the Apple class.
An object of the Human class eats an object of the Orange class.
If the classes that an object from the Human class can eat were expanded to more than just Apple and Orange, we would need to add more relations...
