Object-oriented programming

So today, I plan to start learning chapter 5. But before that, I need to review what is object-oriented programming, and some basic concepts.

1) Object-oriented programming (OOP) is a programming paradigm that represents concepts as "objects" that have data fields (attributes that describe the object) and associated procedures known asmethods. Objects, which are usually instances of classes, are used to interact with one another to design applications and computer programs.

2) Class is a construct that is used to create instances of itself – referred to as class instances, class objects, instance objects or simply objects. A class defines constituent members which enable its instances to have state and behavior.

3) Object is a location in memory having a value and referenced by an identifier. An object can be a variable, function, or data structure. With the later introduction of object-oriented programming the same word, "object," refers to a particular instance of a class.

4）Method is a subroutine (or procedure) associated with a class. Methods define the behavior to be exhibited by instances of the associated class at program run time. Methods have the special property that at run-time  they have access to data stored in an instance of the class (or class instance or class object or object) they are associated with and are thereby able to control the state of the instance.

5）Instance is an occurrence or a copy of an object, whether currently executing or not. Instances of a class share the same set of attributes, yet will typically differ in what those attributes contain.

I also learnt the three main differences between object-oriented and process-oriented. They are Inheritance, Encapsulation,Polymorphism. Since they are so complicated, it is better not describe them in detail here.