C# is an object-oriented programming language, which means it’s built around the concept of objects — self-contained pieces of code that contain both data and behaviour. These objects are created from classes, which act like blueprints.
Understanding classes and objects is a core skill in C#. They help you build structured, reusable, and scalable programs.
In this post, we’ll break down what classes and objects are, why they’re useful, and how to define and use them in your own C# code.
🏗️ What Is a Class?
A class is a user-defined type that describes what an object should contain. It defines:
- Fields (also called variables or properties)
- Methods (functions that act on the data)
Think of a class as a template — like a blueprint for a car. It describes the components and behaviours, but no actual car exists until you build one — that’s the object.
🔹 Example: Class Definition
public class Person
{
// Fields or Properties
public string Name;
public int Age;
// Method
public void Introduce()
{
Console.WriteLine($"Hi, I'm {Name} and I'm {Age} years old.");
}
}
👤 What Is an Object?
An object is a real-world instance of a class — an actual “thing” in memory that you can use.
🔸 Creating and Using an Object
Person person1 = new Person();
person1.Name = "Alice";
person1.Age = 30;
person1.Introduce();
This creates an object of type Person, sets its data, and calls a method.
🧪 Another Example
Let’s create a simple Car class and use it.
public class Car
{
public string Make;
public string Model;
public int Year;
public void Honk()
{
Console.WriteLine("Beep beep!");
}
}
🛻 Using the Car Class:
Car myCar = new Car();
myCar.Make = "Toyota";
myCar.Model = "Corolla";
myCar.Year = 2022;
Console.WriteLine($"{myCar.Make} {myCar.Model}, {myCar.Year}");
myCar.Honk();
🧠 Why Use Classes and Objects?
✅ Organise code logically
✅ Group data and behaviour together
✅ Reuse code across your program
✅ Scale easily by creating multiple objects from one blueprint
🧰 Recap of Key Terms
| Term | Meaning |
|---|---|
| Class | A blueprint for creating objects |
| Object | An actual instance of a class |
| Property | A variable inside a class |
| Method | A function defined inside a class |
new | Keyword used to create (instantiate) an object |
🧪 Challenge
Try writing a Book class with properties Title, Author, and Pages, and a method Describe() that prints a description of the book.
📚 Summary
Classes and objects are the building blocks of object-oriented programming. By defining your own classes and creating objects from them, you can write cleaner, more powerful C# applications that reflect real-world ideas and behaviours.
📬 Need help designing your own classes or understanding object-oriented thinking? Contact us — we’re happy to help you build confidence and structure your code the right way.