Diet Pepsi is a no-calorie carbonated cola soft drink produced by PepsiCo, introduced in 1964 as a variant of Pepsi with no sugar. First test marketed in 1963 under the name Patio Diet Cola, it was re-branded as Diet Pepsi the following year, becoming the first diet cola to be distributed on a national scale in the United States.
In the 1960s and 1970s its competition consisted of Tab, produced by The Coca-Cola Company, and Diet Rite cola, produced by RC Cola. Diet Coke.
While the U.S. represents the largest single market for Diet Pepsi, it was launched in the UK.