C# Classes and Objects: Complete Guide

What Is a Class in C#?

A class is a blueprint that describes the data and behavior an object can have. A class can contain fields, properties, methods, constructors, events, and other members.

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

    public void Display()
    {
        Console.WriteLine($"{Name} - {Age}");
    }
}

What Is an Object?

An object is an instance of a class. The new keyword creates the object and allocates the required memory.

Employee employee = new Employee
{
    Name = "Dhilip",
    Age = 31
};
employee.Display();

Properties

Properties provide controlled access to data stored by an object. Auto-properties are commonly used in modern C# applications.

public string Name { get; set; }
public decimal Salary { get; private set; }

Constructors

A constructor runs when an object is created. Constructors are useful for establishing valid initial state.

public class Product
{
    public string Name { get; }
public Product(string name)
{
Name = name;
}
}

Methods

Methods define behavior for a class.

public decimal CalculateTotal(decimal price, int quantity)
{
    return price * quantity;
}

Access Modifiers

Common access modifiers include public, private, protected, and internal. Prefer the least visibility required by your design.

Class vs Object

Class	Object
Blueprint or definition	Instance of a class
Defines members	Contains actual state
Does not represent one specific entity	Represents a specific entity

Best Practices

• Keep each class focused on a clear responsibility.
• Prefer properties over public fields for application models.
• Use constructors to enforce required state.
• Keep implementation details private when possible.
• Use meaningful class, property, and method names.

Conclusion

Understanding classes and objects gives you the foundation needed for inheritance, interfaces, dependency injection, Entity Framework Core, ASP.NET Core, and most modern C# application development.