It may seem brilliant now, and may have even seemed brilliant in 1982, given that arch rival Pepsi had been producing a diet version of its flagship brand (Diet Pepsi, nee Patio Diet Cola) since 1964. But Coke, the most popular soft drink in the world and one of it’s strongest brands, already had a very successful diet product, Tab. So the decision to risk brand equity—Diet Coke was the first new product since 1886 to use the Coca-Cola trademark—was not the obvious course. But it was a wise one. Last year, Diet Coke passed Pepsi to become the second-most popular soda in the U.S., behind Coke.