OOP is a design philosophy. It stands for Object Oriented Programming. To take the Object Oriented approach is a more effective way to program. Details:OOP in .NET mit C#,VB.NET(German).

Before you can begin with OOP, it s essential to be acquainted with the terminology used.

Class
A class is a blueprint or prototype that defines the variables and the methods common to all objects of a certain kind. It is a programmer defined type that serves as a template for instances of the class. A class is a template that specifies the attributes and behavior of something. Used in:Verteilte Anwendungen mit der Windows Communication Foundation - WCF(German).

Object
An Object is an instance of a class. If you look around you, you will see objects everywhere. It is a software bundle of related state and behavior. Objects are the crucial run-time entities in an object-oriented system.

Behavior
The behavior of objects is defined in member-functions. Real-world objects share two characteristics: They all have state and behavior.

State
The state is what data the object holds. Hence objects of a class are similar except for their state.

Abstraction
Abstraction is the ability of a program to ignore the details of an object’s class and work at a more generic level when suitable. It is considered one of the most important concepts of software development.

Encapsulation
Encapsulation is the process of keeping data and methods together inside objects. It combines one or more information into a component. The concept of encapsulation is the best strategy to break down complex business cases into small, manageable units. Encapsulation is one of the fundamental OOP concepts. An excellent way to improve your teams C-Sharp skills, is by booking a Dotnet-Seminar(German).

The use of Object Oriented design and OOP are becoming increasingly popular. At its heart, OO programming is about creating distinct packets or groupings of data, what we call objects that model some thing in the application space.