What is cream of tartar and how important is it in a recipe?

What is it made from? What does it do? I have a recipe that calls for 1/4 teaspoon of it, that seems so small, what happens if I don't use it?What is cream of tartar and how important is it in a recipe?
Go to this link


http://www.ochef.com/933.htm


And go down to where the paragraph starts... ';Cream of tartar is best known in our kitchens for helping stabilize and give more volume to beaten egg whites.'; and read down from there. It gives a little information about substituting for cream of tartar, but yes, 1/4 tsp is a small amount, but I would not go ahead and make the recipe without using cream of tartar, or finding a suitable substitute. It probably wont turn out.What is cream of tartar and how important is it in a recipe?
It stabilizes acidity and allows food to rise.
What are you trying to make? Cream of Tartar is often used as a stabilizer in meringues.