Now for a little background (my favorite part):

Cola is a sweet carbonated drink usually containing caramel coloring and caffeine. It was originally invented by John Stith Pemberton when he was a druggist and chemist in Columbus, Ohio working on a coca and cola (kola) nut beverage. It was intended to stop headaches and calm nervousness, but others insist he was attempting to create a pain reliever for himself and other wounded Confederate veterans. He began this process at his laboratory, but soon after the war, moved his entire operation to Atlanta.

Despite the name, the primary flavoring ingredients in cola are sugar, vanilla, cinnamon and (usually) caffeine; different manufacturers of cola drinks add other trace ingredients to the drink in addition to these flavorings in order to create distinctively different tastes for each brand. Trace flavorings may include orange, nutmeg, and a wide variety of other ingredients, but the base flavorings that most people identify with cola taste remain vanilla and cinnamon. Kola nuts, which have a bitter taste, contribute little or no flavor to most cola recipes. Acidity is often provided by citric acid, although Coca-Cola uses phosphoric acid for a more neutral (less fruity) taste.

Inexpensive colas may contain only vanilla and cinnamon as flavorings, which provide a simple cola taste. Many cola drink recipes are closely-guarded secrets of their manufacturers, with the recipe used by Coca-Cola being perhaps the most famous. In fact, in the summer of 2006. three people including a Coke employee were arrested for trying to sell their ultrasecret recipe to Pepsi. They didn't contemplate Pepsi turning to the FBI for advice.

In addition to high fructose corn syrup, many other sweeteners may be used as the sweetening ingredient in cola, including sugar, stevia, or an artificial sweetener depending on product and market. "Sugar-free" or "diet" colas contain artificial sweeteners only. Caffeine-free cola drinks are also available.