# Solution

*noun*

say it: **“suh-LOO-shun”** **/səˈluːʃən/**

A Visual Studio file that groups related projects, such as an app and its tests, so they open and build together.

## What is **Solution** in C#?

**Solution** — A file that groups related projects, such as an app and its test project, so Visual Studio opens them together and builds them in one go. In .NET 10 it is a `.slnx` file; older ones end in `.sln`.

```bash
dotnet new sln --name Scoreboard        # Scoreboard.slnx
dotnet sln add Scoreboard.App Scoreboard.Tests
```

## In a sentence

- “I added the test project to the **solution**, so one build compiles both the app and its tests.”

Level: Apprentice · [More C# terms at this level](https://www.ask-codey.com/glossary?category=c-sharp&level=2)

Updated: October 28, 2026

Source: https://www.ask-codey.com/glossary/solution