Adding params keyword itself shows that you can pass multiple number of parameters while calling that method which is not possible without using it. To be more specific:
static public int addTwoEach(params int[] args)
{
int sum = 0;
foreach (var item in args)
{
sum += item + 2;
}
return sum;
}
When you will call above method you can call it by any of the following ways:
addTwoEach()
addTwoEach(1)
addTwoEach(new int[]{ 1, 2, 3, 4 })
But when you will remove params keyword only third way of the above given ways will work fine. For 1st and 2nd case you will get an error.