Why should you care?

Every feature — EF Core, Identity, MVC — gets wired here. When something is not registered, you will debug Program.cs first.

See it live — copy this example

Create an MVC project (dotnet new mvc), add the code, and run dotnet run.

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddControllersWithViews();

var app = builder.Build();
app.UseStaticFiles();
app.UseRouting();
app.MapControllerRoute(
    name: "default",
    pattern: "{controller=Home}/{action=Index}/{id?}");
app.Run();

Run Example »

Edit the code and click Run — like W3Schools Try it Yourself.

What happened?

• CreateBuilder loads appsettings.json.
• AddControllersWithViews registers MVC.
• Middleware order matters: static files, routing, then endpoints.

Try it yourself

1. Open Program.cs in ShopNest.
2. Add a comment above each line explaining its job.
3. Temporarily comment UseStaticFiles — refresh and see CSS disappear.
4. Change text or labels in the example and run again — watch the browser update.
5. Break the code on purpose (remove a semicolon), read the error message, then fix it.

Remember

Program.cs = configure services + middleware pipeline. AddControllersWithViews enables MVC. Order of Use* calls is critical.