C#/.NET + VisualStudio, namespace problem

I have started learning C#/.NET/VisualStudio (2022) and have this strange problem; all the methods/classes in System and it’s nested namespaces seem to be available without full path or using directives at beginning.

E.g. the following example compiles just fine:

// Program.cs
namespace MyApp
{
    internal class Program
    {
        static void Main()
        {
            Console.WriteLine("Hello World!"); //System.Console
        }

        static HttpClient client = new HttpClient(); //System.Net.Http.HttpClient
    }
}

Why this happens and can I disable this behavior somehow?

>Solution :

If you are using .NET 6, this is likely from a new feature called "Implicit Usings". Depending on your project type, certain namespaces are automatically included. For example, the default console app template implicity includes the following namespaces:

• System;
• System.IO;
• System.Collections.Generic;
• System.Linq;
• System.Net.Http;
• System.Threading;
• System.Threading.Tasks;

You can disable this feature by including the following in your project file:

<PropertyGroup>
   <ImplicitUsings>disable</ImplicitUsings>
</PropertyGroup>

There is further documentation on this feature and "Global Usings" in this Microsoft documentation.