Classes and objects are the foundation of Object-Oriented Programming (OOP).
If you understand classes and objects properly, the rest of OOP becomes easy.

In this lesson, you will learn:

• What is a class?
• What is an object?
• How to create classes and objects in C#
• Properties, fields, and methods
• Real-world examples
• Practical C# examples

🌟 What is a Class in C#?

A class is a blueprint or template for creating objects.

✔ Simple Definition:

A class defines how an object will look and behave.

It contains:

• Fields (variables)
• Properties (get/set values)
• Methods (actions)
• Constructors
• Events (advanced)

🟩 Real-World Analogy of a Class

✔ Class = Car Blueprint

The blueprint defines:

• Color
• Model
• Speed
• Features

But you cannot drive the blueprint.
You can only drive a real car, which is the object.

🌟 What is an Object in C#?

An object is an instance of a class.

✔ Simple Definition:

Object = something created from a class.

If class = blueprint,
then object = real product.

🧑‍💻 Basic Class & Object Example in C#

✔ Step 1: Create a Class

public class Car
{
    public string Brand;
    public string Color;

    public void Start()
    {
        Console.WriteLine($"{Brand} is starting...");
    }
}

✔ Step 2: Create an Object from Class

Car myCar = new Car();
myCar.Brand = "Honda";
myCar.Color = "Red";

myCar.Start();  

Output:

Honda is starting...

✔ Car is the class
✔ myCar is the object

🧱 Components of a Class

A class usually contains:

1️⃣ Fields (Variables inside class)

public string name;
public int age;

2️⃣ Properties (Encapsulated fields)

public string Name { get; set; }
public int Age { get; set; }

3️⃣ Methods (Actions or behaviors)

public void Speak()
{
    Console.WriteLine("Hello!");
}

4️⃣ Constructors (Special method to initialize objects)

public Person(string name)
{
    Name = name;
}

🔍 Detailed Example — Student Class

✔ Class Definition

public class Student
{
    public string Name;
    public int Age;

    public void Study()
    {
        Console.WriteLine($"{Name} is studying.");
    }
}

✔ Object Creation

Student s = new Student();
s.Name = "Amit";
s.Age = 20;

s.Study();

Output:

Amit is studying.

🌈 Multiple Objects from One Class

Car car1 = new Car();
car1.Brand = "BMW";

Car car2 = new Car();
car2.Brand = "Audi";

car1.Start();  // BMW is starting...
car2.Start();  // Audi is starting...

✔ Both objects share the same blueprint
✔ But hold different data

🧠 Why Do We Use Classes & Objects?

✔ Reusability

Create once → use many times.

✔ Organization

Separate data and behavior properly.

✔ Modularity

Divide large applications into smaller classes.

✔ Real-world modeling

Makes programming intuitive.

✔ Code maintenance

Change in one place affects all instances.

🎯 Real-World Examples of Classes

🧩 Practical Example — Product Class

✔ Class:

public class Product
{
    public string Name;
    public double Price;

    public void Display()
    {
        Console.WriteLine($"Product: {Name}, Price: {Price}");
    }
}

✔ Objects:

Product p1 = new Product();
p1.Name = "Laptop";
p1.Price = 55000;

Product p2 = new Product();
p2.Name = "Mouse";
p2.Price = 500;

p1.Display();
p2.Display();

🔎 Classes vs Objects (Easy Table)

📝 Mini Exercise

Create a class named Mobile with:

Properties:

• Brand
• Model
• Price

Method:

• Details() → prints all details

Then create two objects with different values.

🔍 FAQs

Q1: Can a class exist without an object?

Yes, but you cannot use it until you create an object.

Q2: How many objects can be created from one class?

Unlimited.

Q3: Can a class have multiple constructors?

Yes, constructors can be overloaded.

Q4: Is a class a reference type?

Yes, classes are reference types in C#.

🎉 Conclusion

Classes and objects form the building blocks of C# and OOP.
A class defines the structure, and objects bring it to life.

You now understand:

✔ What is a class
✔ What is an object
✔ How to create classes
✔ How to create objects
✔ Real-world analogies
✔ Why classes & objects matter