What Is .NET? A Beginner's Guide

.NET is Microsoft's development platform for building web, desktop, cloud, mobile, and other applications. C# is one of the main languages used with it, but .NET also supports other languages and application models.

.NET runtime

The .NET runtime provides the environment that executes managed .NET applications. It loads the application and the libraries it uses and provides services required while the application runs.

.NET SDK

The SDK provides the command-line tools and templates used to create, build, test, and publish .NET applications. Check your installed SDK with:

dotnet --info

Create and run a project

dotnet new console -n HelloDotnet
cd HelloDotnet
dotnet build
dotnet run

dotnet new creates a project from a template, dotnet build compiles it, and dotnet run builds and starts it from the command line.

What is a project?

A project contains source code, configuration, dependencies, and build information. The project file, such as a .csproj file, tells the SDK how the application should be built. A solution can contain multiple related projects.

What is NuGet?

NuGet is the package ecosystem used to add reusable libraries to .NET applications. Dependencies are normally declared in the project file and restored by the .NET tooling.

Frameworks, runtimes, and SDK versions

A target framework describes the .NET API surface an application is built for. The SDK is the development toolset, while the runtime executes applications. Keeping these concepts separate makes version and deployment problems easier to diagnose.

Common beginner mistakes

• Running commands from a directory that does not contain the expected project.
• Installing only a runtime when development requires an SDK.
• Assuming every NuGet package is automatically compatible with every target framework.

Next step

Explore the .NET Tutorials pillar for dependency injection, configuration, APIs, package management, and other practical topics.