.net problem

i cant understand the last coding of function parameters...please explain the whole program... static void Main(string[] args)
{
GreetPersons(0);
GreetPersons(25, "John", "Jane", "Tarzan");
Console.ReadKey();
}

static void GreetPersons(int someUnusedParameter, params string[] names)
{
foreach(string name in names)
Console.WriteLine("Hello, " + name);
}


please explain line by line...thank u