What is dotnetcore?

dotnetcore, now called .NET 5+ or just .NET, is a free, open‑source, cross‑platform framework from Microsoft that lets developers build applications (websites, mobile apps, desktop programs, cloud services, etc.) using languages like C# and F#. It runs on Windows, macOS, and Linux, and provides a common set of libraries and a runtime to execute the code.

Let's break it down

  • Runtime: The part that actually runs your compiled code on any OS. It’s called the .NET runtime (formerly CoreCLR).
  • Libraries: Pre‑written code (called the Base Class Library) that handles everyday tasks such as file I/O, networking, and data handling.
  • SDK (Software Development Kit): Tools you install on your computer to write, build, and publish .NET apps (includes the compiler, command‑line tools, and templates).
  • Languages: Primarily C#, but you can also use F# and Visual Basic.
  • Cross‑platform: The same code can be compiled once and run on Windows, Linux, or macOS without changes.

Why does it matter?

Because it lets developers create one codebase that works everywhere, saving time and money. Being open‑source means the community can contribute improvements, and the frequent updates keep it modern and secure. It also integrates tightly with popular tools like Visual Studio and Azure, making it a strong choice for enterprise and indie projects alike.

Where is it used?

  • Web APIs and websites built with ASP.NET Core.
  • Desktop apps using Windows Forms, WPF (Windows only) or cross‑platform UI frameworks like MAUI.
  • Mobile apps via .NET MAUI or Xamarin.
  • Cloud services and micro‑services on Azure, AWS, or Google Cloud.
  • Game development with Unity (which uses a version of .NET).
  • IoT devices and command‑line utilities.

Good things about it

  • Cross‑platform: Write once, run anywhere.
  • High performance: Compiled to native code, fast execution.
  • Rich ecosystem: Thousands of NuGet packages and libraries.
  • Strong tooling: Excellent IDE support (Visual Studio, VS Code).
  • Open source: Transparent development and community contributions.
  • Long‑term support (LTS) versions provide stability for production apps.

Not-so-good things

  • Learning curve: New to .NET developers must grasp the runtime, SDK, and project structure.
  • Ecosystem fragmentation: Older .NET Framework projects may need migration to .NET 5+.
  • Platform quirks: Some libraries still behave differently on Linux vs. Windows.
  • Size: The runtime can be larger than lightweight alternatives for small utilities.
  • Rapid changes: Frequent releases mean you need to keep up with updates to avoid compatibility issues.