csproj

A csproj is the C# project file used by the .NET build system MSBuild. It is an XML file with the .csproj extension that describes how to build a C# project, its dependencies, and related metadata. The file is typically located at the root of a project and is read by tools such as Visual Studio and the dotnet CLI.

The content of a csproj resides in XML elements such as Project, PropertyGroup, ItemGroup, and Target. PropertyGroup contains build settings like OutputType (Exe or Library), AssemblyName, RootNamespace, and TargetFrameworks. ItemGroup lists items that participate in the build, including Compile items (C# source files), None, Content, EmbeddedResource, as well as references via ProjectReference and PackageReference. The project file may also include Import statements and custom Targets to extend the build process.

SDK-style csproj: Since the advent of .NET Core, a simplified project format, the SDK-style csproj uses a single Project element with an Sdk attribute (for example, Microsoft.NET.Sdk) and relies on implicit conventions. It typically declares TargetFramework or TargetFrameworks and PackageReference entries for NuGet dependencies, instead of older packages.config. Projects can reference other projects with ProjectReference.

Legacy (non-SDK) csproj: Older project formats include more verbose XML with explicit ItemGroup definitions for each file and a separate packages.config for NuGet dependencies. They can be more cumbersome to maintain and often require more boilerplate metadata.

Usage and tooling: The csproj is processed by MSBuild and is manipulated by tools such as Visual Studio, VS Code with the C# extension, and the dotnet CLI (dotnet build, restore, run, publish, pack). It can be edited directly and supports central configuration through mechanisms like Directory.Build.props and Directory.Build.targets.