From .NET Framework to .NET Core and Unification (.NET 5-9): The Silent Revolution of Microsoft Development

Introduction

Do you remember the days when .NET development meant being chained to Windows, Visual Studio, and those gray, lifeless forms? If you ever coded with WinForms or struggled with the early framework versions, this story is yours too. But if you joined .NET in the multiplatform era, get ready to discover how Microsoft quietly transformed the DNA of its flagship platform.

The Evolution of .NET: A Timeline of Innovation

2002-2015: The Reign of .NET Framework on Windows

In 2002, Microsoft launched .NET Framework 1.0: a bold bet to unify development on Windows, supporting multiple languages (C#, VB.NET, F#).
Developers cheered for library reusability, the power of Visual Studio, and the famous IntelliSense.

csharpCopiarEditar// Classic WinForms example in .NET Framework
using System.Windows.Forms;

Application.Run(new Form
{
    Text = "Hello WinForms!",
    Width = 400,
    Height = 200
});

Fun fact:
WinForms, although visually limited, enabled the creation of thousands of enterprise apps that still survive.
For over a decade, .NET was synonymous with “Windows desktop applications.”

2016-2019: .NET Core is Born — The Leap to Cross-Platform

The industry changed. Software needed to run on Windows, Linux, and macOS. Microsoft, once dismissive of open source, surprised the world by launching .NET Core:

• Open source from day one

• Cross-platform execution

• Noticeable improvements in performance and modularity

csharpCopiarEditar// Cross-platform "Hello World" with .NET Core
using System;

Console.WriteLine("Hello world from .NET Core!");

Fun fact:
The .NET Core source code lives on GitHub. Anyone can contribute.

.NET Core was the first step to break free from Windows. With .NET Core 3.0, WPF and WinForms returned to Windows, but the ecosystem was freer than ever.

2020 and Beyond: Unification and Modernization (.NET 5-9)

In 2020, Microsoft made the dream a reality: unifying .NET Framework and .NET Core into a single platform:

• .NET 5 kicked off the modern era: cross-platform, high performance, web, mobile, desktop, AI, and cloud development with a single codebase.

• Later versions (6, 7, 8, and 9) brought continuous improvements in performance, minimalism (minimal APIs), AI integration, native ARM support, and new web/cloud-native development capabilities.

csharpCopiarEditar// Minimal API in .NET 6+
var app = WebApplication.Create(args);
app.MapGet("/", () => "Hello from Unified .NET!");
app.Run();

Fun fact:
Starting with .NET 5, C# evolves in step with the runtime. Releases are yearly and open source.

Final Reflection: A Reinvented Legacy

From gray desktop apps to the cloud and AI, .NET’s story is a lesson in adaptation, community, and vision.
Today, being a .NET developer means being part of a global, cross-platform, open movement.

What was your first .NET project?

Share in the comments, spread the article, and keep exploring how platforms evolve. The future of .NET is just beginning!