30 years of Diet Coke

This year marks the 30th anniversary of the world's third-most popular soft drink, Diet Coke. Introduced in 1982, Diet Coke was the first extension of the Coke trademark and, at the time, The Coca-Cola Company's most carefully researched product. Since 1984, the soda has remained the most popular diet soft drink on the planet. Here's a retrospective look at the iconic brand.

Caffeine-free Diet Coke

Coke entered the caffeine-free market in May 1983, when Coca-Cola USA's then-president Brian Dyson declared that caffeine-free Diet Coke would be available to 80 percent of the U.S. population and dominate the market by the following year.

"Coke's entry into the market -- which it had scorned when competitors took out the caffeine last year -- was in response to consumer demand," Dyson told the Associated Press on May 15, 1983.

Diet Coke's "Stay Extraordinary" can

Coca-Cola brought "extraordinary style to the soft drink aisle" in September 2011, when it introduced a hipper-looking can for its iconic Diet Coke brand. Turner Duckworth, a San Francisco-based design agency, designed the limited-edition packaging, a new look for last fall. In March 2010, The Coca-Cola Company (KO) launched a new Diet Coke marketing campaign that focused on how the brand helps young adult Diet Coke drinkers get the most out of life, the company said in a statement.

Diet Coke Black Cherry Vanilla

The Coca-Cola Company distributes Diet Coke Black Cherry Vanilla only in Canada and the United States.

Diet Cherry Coke

The Coca-Cola Company (KO) distributes its calorie-free Diet cherry Coke in Great Britain and the United States. The soda aims to enliven without guilt, according to Coca-Cola.

Diet Coke Heart Truth can

Last February, American Heart Month 2011, The Coca-Cola Company (KO) distributed limited-edition cans of Diet Coke in support of The Heart Truth campaign, an effort by the National Heart, Lung and Blood Institute to raise awareness and funds for women's heart health education and research, according to Coca-Cola. Coke said it expected to include The Heart Truth's Red Dress logo on more than 6 billion packages of Diet Coke.

Diet Coke sweetened with Splenda

Diet Coke sweetened with Splenda, a taste of Diet Coke with no real or artificial sugar, was created by The Coca-Cola Company (KO) in 2005 in response to consumers who told Coke that they enjoyed the tastes of Splenda and Diet Coke, and wanted the company to put the two together, according to Coca-Cola.

Diet Coke by Jean Paul Gaultier

Recreating Jean Paul Gaultier's "Night & Day" designs for The Coca-Cola Company's (KO) Diet Coke brand, a model is seen posing on April 16, 2012, at Harvey Nichols in London, England.

Diet Coke by Karl Lagerfeld

Karl Lagerfeld Diet Coke bottles — The Coca-Cola Company (image), Jason Henry McCormick/CBS (text)

Renowned designer Karl Lagerfeld joined forces last year with The Coca-Cola Company (KO), creating three new looks for Diet Coke's aluminium bottle.

"I love this bottle but it's time for a new one. Actually I want to do three bottles," Lagerfeld said in March 2011.

The same year, Diet Coke surpassed Pepsi as America's second-most popular soft drink.

Diet Coke 25th Anniversary sleek can

In 2007, Diet Coke celebrated a quarter-century of thirst quenching by packaging its secret formula in this slim can for a limited time.