//Tells the complier that this program uses types from the System namespace.
using System; 
//Declares a new namespace, called HelloWorld
//A namespace is a set of type declarations associated with a name.
namespace HelloWorld 
{
    //Declares a new class type, called Program
    class Program
    {
        //Declares a method called Main as a member of class Program
        //Main is a special function used by the complier as the starting point of the program.
        static void Main(string[] args)
        {
            //Contains only a single, simple statement; this line constitutes the body of Main.
            //Simple statements are terminated by a semicolon.
            //This statement uses a class called Console, in namespace System, to print out the message to a window on the screen
            //Without the using statement in line 1, the compiler wouldn‘t have known where to look for class Console.
            Console.WriteLine("Hello World!");
        }
    }
}