Simple on the surface. Confusing in practice. I get why—terms get mixed up all the time. I’ll be honest: when I explain this to people, I start with one sentence. That sentence changes everything.
C# is a programming language. .NET is the platform that runs code written in C# (and other languages). Say that out loud to someone who’s stuck—watch their face relax. That’s the hook. Stick with me and I’ll walk you through real examples, common mistakes, a step-by-step setup, and tools I recommend.
C# versus .NET — the simple split
What C# actually is
C# is like the words and grammar you use to write a letter. You write code in C#. It has variables, loops, classes, and syntax rules. If you know Java or JavaScript, C# feels familiar. I find it clean, predictable, and strong-typed—so many developers like that.
What .NET actually is
.NET is more like the post office, the envelopes, and the sorting machines. It includes the runtime (CLR), libraries (BCL), tools (CLI), and a way to build and run apps on Windows, Linux, macOS, mobile, cloud, and more. You write in C#, then the .NET runtime runs your code.
How they work together — a tiny story
Here’s a composite story I use often: a small team needed an API and a web UI. One dev said “We’ll use C#.” Another said “We’ll use .NET.” The truth? They used C# to write the API code and .NET (the runtime and libraries) to run that code on the server. Two words, same project, different roles. That cleared the entire meeting.
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Detailed comparison (table)
| Thing | What it is | What you do with it |
|---|---|---|
| C# | Programming language | Write classes, methods, and logic |
| .NET | Runtime, libraries, and SDK | Run apps, manage memory, use built-in APIs |
When to choose what
Here’s the deal: choose the language for style, team skill, or interop needs. Choose the platform for deployment, performance, or libraries.
- Pick C# if you like its syntax, safety, and rich features (async, LINQ, records).
- Pick .NET when you need a cross-platform runtime, solid web frameworks, or Azure-friendly tooling.
Step-by-step: start a small C# + .NET project (quick)
- Install the .NET SDK from the official site or your package manager.
- Open a terminal and run:
dotnet new console -n MyApp. - Open the created folder in Visual Studio or another editor.
- Edit
Program.csusing C# code. - Run
dotnet runand watch it execute on .NET runtime.
Common mistakes (real things I see)
- Thinking C# = .NET. They’re related, but not the same. Big source of confusion.
- Choosing “.NET Framework” when you want cross-platform. Nowadays .NET (Core/5/6+) is the cross-platform line.
- Trying to use a package that targets an older .NET and getting cryptic build errors.
- Assuming a C# update always needs a .NET update. Not always true—sometimes it’s the other way around.
Tool recommendations
Here are tools devs use daily. I mention them because they make the difference between a rough day and a smooth one.
- Visual Studio — full IDE for Windows, feature-packed.
- Visual Studio Code + C# extension — light, cross-platform.
- JetBrains Rider — great if you like IntelliJ-style tooling.
- dotnet CLI — essential for quick scaffolds and CI scripts.
- NuGet — package manager for .NET libraries.
Specific examples with numbers
Okay — concrete numbers, but framed clearly: in a typical small team scenario I describe, switching from a mixed-stack to a unified C# + .NET stack often cuts friction. For example, a hypothetical small team moving API and worker code into .NET could reduce the number of different runtimes from three to one—less ops work, fewer bugs at integration time. That might drop deploy errors from, say, 8 per month to 3 per month. Those numbers are illustrative; they show the scale of possible gains.
FAQ
Quick, straight answers. I’ll keep these short—like chatting over coffee.
Q1: What is the difference between C# and .NET?
A: C# = the language you type. .NET = the runtime and libraries that run your typed code.
Q2: Is C# part of .NET?
A: C# is not “part of” .NET in the sense of being the runtime, but it was made for .NET and is tightly supported by it.
Q3: Can I use other languages on .NET?
A: Yes — VB.NET, F#, and others can run on .NET too. C# is just the most popular.
Q4: Which is faster: C# code or .NET code?
A: That’s a mixed question. C# code runs on .NET, so performance depends on how you write code and which .NET runtime you use.
Q5: Should I learn C# or .NET first?
A: Start with C# basics to get comfortable writing code. Then learn .NET pieces (runtime, libraries, CLI) so you can run and ship apps.
Recommendations
Here’s what I’d do if I were building something right now: start small, write a tiny console app in C#, and run it with the .NET SDK. Try one web endpoint with ASP.NET Core. Test deploy to a free tier (or local Docker). If you like fewer moving parts, keep C# + .NET as your core stack.
