Those two colorful letters are so familiar that “M&M” almost feels like a word of its own, but the initials have a specific origin. The name M&M’s comes from the surnames of the two men involved in creating and launching the product: Forrest Mars Sr. of the Mars candy company and William F. R. Murrie, whose father was president of Hershey at the time. Their collaboration brought together Mars’ business ambitions and Murrie’s connections to the chocolate industry, giving the new candy its famous name with each letter representing one of the men.

The story starts in the late 1930s, when Forrest Mars was looking for a way to create a chocolate candy that could withstand warmer temperatures. According to the company’s history, Mars was inspired by soldiers eating “chocolate pellets coated with a hard sugar shell during the Spanish Civil War.” The coating helped keep the chocolate from melting, leading to the official U.S. launch in 1941.

The sugar shell served a vital practical purpose. Chocolate naturally melts when exposed to heat, so a firm sugar coating creates a protective layer that keeps the treat easy to carry and store. This feature was particularly useful during World War II when the candies became associated with military rations, as they could travel “without creating quite the chocolatey mess that an uncoated chocolate bar might cause.”

Once you know what the initials mean, the little “m” printed on every single piece becomes hard to miss. That mark has become one of the most recognizable features of the product. The candies originally appeared in limited colors, but the selection expanded over the decades, and today the colorful assortment makes the product instantly recognizable.