Program.cs and hosting

Modern ASP.NET Core uses a minimal Program.cs entry point—top-level statements configure the host, services, and middleware pipeline. This replaced the older Startup.cs split in many templates.

Minimal hosting model (.NET 6+)

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

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

What happens at startup

1. WebApplication.CreateBuilder loads configuration and logging
2. Services registered in DI container (AddControllers, AddDbContext)
3. Middleware pipeline built (Use* then Map*)
4. Run() starts Kestrel and blocks until shutdown

Important interview questions and answers

1. Q: Program.cs vs Startup.cs?
   A: .NET 6+ merges both into Program.cs; older tutorials split ConfigureServices/Configure.
2. Q: What is WebApplication?
   A: Combined host + pipeline builder simplifying bootstrapping.

Self-check

1. Where do you register services for DI?
2. What method starts the web server?