In some situations, it can prove to be useful and convient to have a function that can accept X number of parameters.
For example:

At point A you'll write a function to add 3 integers together, and of course it'll only accept three parameters.
At point B, you'll need an identical function, but which can accept 10 integers.

So instead of doing the typical 1 + 2 + 3 + 4 etc. (this can very tedious to do, especially with more than let's say 15 numbers), you'll make a function that can accept as many (or as few) arguements as you'll ever need.

Following is an example of a function that accepts N number of arguements, adds the passed numbers together and returns the result.

function AddNumbers( const ArgsList : array of const ) : Integer;
var
  ArgsListTyped: array[0..$FFF0 div SizeOf(TVarRec)] of TVarRec absolute ArgsList;
  n: Integer;
begin
  result := 0;
  for n := Low( ArgsList ) to High( ArgsList ) do
  begin
    with ArgsListTyped[ n ] do
    begin
      case VType of
        vtInteger: result := result + VInteger;
      end;
    end;
  end;
end;

// AddNumbers() will return the sum of all the integers passed to it
{
  AddNumbers( [1, 2, 3] ); will return 6
  AddNumbers( [4, 5, 6, 7, 8, 9, 10, 11] ); will return 60
}

{ Following code was suggested by Luis Ortega.
  Thanks Luis!
}

function AddNumbers( const ArgsList : array of Integer ) : Integer;
var
  n: Integer;
begin
  result := 0;
  for n := Low( ArgsList ) to High( ArgsList ) do
        result := result + ArgsList[n];
end;