Lesson 5 of 62Beginner11 min

Understanding Project Structure

By the end of this lesson

Read a .csproj file and explain what the build output folders contain.

EmployeeTool.csproj

XML

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net10.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

</Project>

OutputType Exe means this produces a runnable program rather than a library.
TargetFramework is the .NET version you are building against.
ImplicitUsings adds common namespaces automatically, which is why you can use Console without writing using System;.
Nullable enable turns on null-safety warnings — covered properly in the modern C# module, and worth leaving on.

Folders that appear after you build:

bin: The build output — the compiled application and everything it needs to run. This is what gets deployed.
obj: Intermediate files used during the build, including dependency resolution results. Working scratch space.

Adding a dependency

Shell

dotnet add package Newtonsoft.Json

This downloads the package and records it in the .csproj file as a PackageReference.
Because it is recorded in the project file, anyone who clones the repository gets the same dependency on their next build. You never commit the package itself.

The .csproj after adding a package

XML

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net10.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
  </ItemGroup>

</Project>

Summary

The .csproj file declares the target framework, output type and dependencies
bin holds deployable build output; obj holds intermediate build files
Neither belongs in version control
dotnet add package records a dependency in the project file, which is what makes builds reproducible

Saved in this browser only.