Vodka is made by the process of distillation of a fermented substance--often potatoes and rye or wheat grain--and less often, sugar beet molasses. The potatoes and grains are heated until the starch is released and converted to sugar. ChaCha again!
Vodka can be made from any fermented organic substance (grain, molasses, etc). The raw materials are mashed, fermented and then distilled (some brands distill vodka several times). It's typically mixed with water for the final product.
Vodka is made from either grain, rye, wheat, potatoes or molasses and sterilized, fermented, then distilled. ChaCha on!