Mountain Dew is a caffeinated citrus-flavored soft drink produced by PepsiCo, Inc. The formula was invented in 1948, and eventually marketed across the United States in 1964. It has a characteristic bright yellow-green and semi-opaque color.
As of 2006, Mountain Dew was the fourth-best-selling carbonated soft drink in the United States, behind only Coca-Cola Classic, Pepsi-Cola, and Diet Coke. Diet Mountain Dew ranked ninth in sales in the same year.