How C# Works · Lesson 9 of 27

.NET SDK

A free lesson from Swipe Coding · C#, level 1 · updated October 2026

By the Swipe team, founded by Colin · how we make lessons

🤖

Time to find out where the compiler and the CLR actually come from. 📦

You now know three building blocks: source code, the compiler (Roslyn), and the CLR. But where do you actually get these tools? The answer: you install the ".NET SDK" (Software Development Kit).

The .NET SDK is a complete package for developers. It contains everything you need to write, build, and run C# programs: the compiler, the CLR, a large collection of ready-made libraries, and the "dotnet" command-line tool that ties it all together.

dotnet build   // Part of the SDK: compiles source code into an assembly
dotnet run     // Part of the SDK: builds and then runs the program

Both of these commands rely on tools bundled inside the .NET SDK.

Fill in the blank

Anyone who wants to write and compile C# programs installs the ____.

🤖

Think of it like a full workshop — everything you need is already inside. 🧰

You can think of the .NET SDK like a complete workshop: it contains not just the machine that runs the finished product (the CLR), but also all the tools needed to actually produce that product in the first place (the compiler and more).

🤖

Not everyone needs the full toolbox, though. 🎬

If you only want to run a finished .NET program without developing your own, a smaller ".NET Runtime" install (which includes just the CLR) is enough. Developers, however, need the full .NET SDK, since it includes the runtime plus the compiler and everything else needed to actually build software.

Quick check

What is included in the .NET SDK?

True or false

You can check whether the .NET SDK is installed correctly by running "dotnet --version".

Chapter quiz