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C# Abstraction

Last Updated : 9 Apr, 2026

Abstraction is the property by which only the essential details are shown to the user and non-essential details or implementations are hidden from the user.

  • It reduces the complexity of viewing things.
  • Avoids code duplication and increases reusability.
  • Helps to increase the security of an application or program as only important details are provided to the user.

Example: Consider a real-life scenario of withdrawing money from an ATM. The user only knows that in the ATM machine first enters the ATM card, then enters the PIN code of the ATM card, and then enters the amount which the user wants to withdraw and at last, they get their money. They don't know about the inner mechanism of the ATM or the implementation of withdrawing money etc. The user just simply knows how to operate the ATM machine, this is called abstraction.

In C# abstraction is achieved with the help of Abstract classes and Interfaces. Both of them are discussed below:

Using Abstract Classes

An abstract class is declared with the help of an abstract keyword. In C#, it is not allowed to create objects of an abstract class. We create a derived class take properties of the abstract class and use them to achieve abstraction. Furthermore, we can access it from the Instance of the derived class object.

  • An abstract class cannot be instantiated directly.
  • It can contain both abstract methods (without implementation) and non-abstract methods (with implementation).
  • Abstract methods must be implemented in derived classes using the override keyword.
  • Abstract classes can have fields, properties, constructors, and methods.
  • An abstract class cannot be declared as sealed.
  • A class cannot be both abstract and static.
  • Abstract methods can only be declared inside abstract classes.

Example:


Output
Area of Square: 16

Using Interfaces

The interface is declared using the interface keyword. We can create abstract methods inside the interface similar to abstract classes and declare their functionality in the derived class. From the derived class we can access those properties using the derived class by creating the Instance of the derived class. Example:


Output
My favorite subject is C#

Abstraction vs Encapsulation

Abstraction and encapsulation are the important features of OOPs. Their functionality is similar and has slight differences which are shown below.

Features

Abstraction

Encapsulation

Definition

Hiding the implementation and exposing the essential details only.

Encapsulate the data and information in a single unit and provide access through accessors.

Implementation

Implements using abstract classes and interface and properties

Implemented using access modifiers in C#

Purpose

Used to hide the complex functionality and show the user-friendly Interface

Provide security and prevent unauthorized data access.

Example

A car class has different features like drive(), brake () and gear() and we can use it without knowing the implementation.

Get () and set() accessors to provide access controls on data.

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