C# - top level instructions

Console.WriteLine("Hello World!");

What is going on here? How can this possibly be valid code? To make a long story short, this is using a new (as of C# 9) feature called "top level statements". You may have noticed that Visual Studio offered a check box saying "don't use top level statements".

The idea is that this makes quick experiments easy to do. Only one file can contain top level statements. The normal way to do business would be:

using System;

namespace Application
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello World!");
        }
    }
}