Diet Coke is the sugar-free version of the Coca-Cola drink. It came about in 1983, when it began to replace Coca-Cola's original sugar-free product, Tab. It uses aspartame as a sweetener.

Seeing that Coca-Cola's rival Pepsi was being successful with its sugar-free brand Diet Pepsi, Coca-Cola decided to launch a new sugar-free brand under the Coca-Cola name to compete with Diet Pepsi. With the well-known name, it could be marketed more extensively than the more anonymously dubbed Tab.

Diet Coke and Diet Pepsi have capitalized on the markets of people who require low calorie regimens, such as diabetics and people with other health conditions, athletes, religious people, and people who want to lose weight.