Ok, stupid question.  What makes vodka ........... Vodka?  I mean, with most alcohols the ingredients define the drink.  Whiskey, scotch, bourbon, tequila, brandy ............. all pretty much (in my experience) use the same ingredients.  Quality may vary, but a grape is still a grape, barley is still barley.  I've seen so many different vodkas at the store ............ vodka made from grapes, vodka made from wheat, vodka made from almost everything I can imagine.  I guess I'm just out of touch, or misinformed when I was younger.  I always think of potatos when I think of vodka.