Introduction to C# (original) (raw)
Last Updated : 22 Apr, 2026
C# (C-sharp) is a modern, object-oriented language created by Microsoft in 2000 as part of the .NET framework. It is used to build Windows applications, web services and more. C# combines the power of C/C++ with the simplicity of Java and Visual Basic.
- Used to build dynamic websites, RESTful APIs, and web services using frameworks like ASP.NET and ASP.NET Core.
- Widely used in the Unity Engine, one of the most popular platforms for developing 2D, 3D, AR, and VR games.
- Supports building Windows desktop applications using WPF and WinForms, as well as cross-platform mobile apps with Xamarin and .NET MAUI.
- Commonly used for developing scalable cloud applications and enterprise software, especially on platforms like Microsoft Azure.
Basic C# Program
C# `
using System;
namespace HelloGeeksApp{
class HelloGeeks{
static void Main(string[] args){
Console.WriteLine("Hello Geek!");
}
}
}
`
Structure of C# Program
The basic structure of a C# program defines the standard way every program must be written otherwise, it may result in errors or unexpected behavior during compilation or execution. The structure includes:
Structure of C# Program
- **Namespace Import: using System; imports the System namespace, which provides fundamental classes such as Console class provides methods for standard input and output operations (such as reading from and writing to the console).
- **Namespace Declaration: namespace HelloGeeksApp groups related classes together and helps organize code while avoiding naming conflicts.
- **Class Declaration: class HelloGeeks defines a class that acts as a container for methods and program logic.
- **Main Method: static void Main(string[] args) is the entry point of the C# program where execution begins. static means the method belongs to the class itself, and void indicates that it does not return any value.
- **Statement: Console.WriteLine("Hello Geek!"); prints the text "Hello Geek!" to the console using the WriteLine method of the Console class.
- **Braces { }: Curly braces define the beginning and end of code blocks such as namespaces, classes, and methods.
Frameworks and Technologies
C# works closely with the .NET ecosystem, which provides the runtime, libraries and tools for application development. Over time, several frameworks and technologies have evolved around C# to support diverse platforms.
Frameworks and Technologies in C#
- ****.NET Framework**: The original Windows-only platform for building desktop and web applications. Commonly used for WPF, WinForms and ASP.NET applications.
- ****.NET Core**: Cross-platform, open-source version of .NET. Used to build apps that run on Windows, Linux and macOS. Supports web APIs, microservices and command-line tools.
- ****.NET 5 and Later (.NET Unified Platform)**: Unifies .NET Framework and .NET Core into a single platform. Provides performance improvements and cross-platform support for all application types.
- **ASP.NET and ASP.NET Core: Frameworks for developing dynamic web applications, RESTful APIs and MVC-based web services.
- **Entity Framework Core (EF Core): Object-Relational Mapper (ORM) for database operations. Allows developers to interact with databases using C# objects instead of SQL queries.
- **Unity Engine: A game development platform that uses C# scripts for game logic. Powers 2D, 3D, AR and VR games across platforms like PC, consoles and mobile.
Advantages
- Automatic garbage collection simplifies memory management.
- Strong type system reduces runtime errors.
- Large standard library and framework ecosystem.
- Cross-platform support with modern .NET versions.
- Excellent tooling in Visual Studio and .NET CLI.