M&M's (styled as m&m's) are "colorful button-shaped chocolates"[1] produced by Mars, Incorporated and similar to and inspired by Smarties. The candy shell, each of which has the letter "m" printed in lower case on one side, surrounds a filling which varies depending upon the variety of M&M's. The original candy had a milk chocolate filling which, upon introducing other variations, was branded as the "plain" variety. "Peanut" M&M's, which feature a peanut coated in milk chocolate, and finally a candy shell, were the first variation to be introduced, and they remain a regular variety. Numerous other variations have been introduced, some of which are regular widespread varieties (such as "peanut butter", "almond", "pretzel", "crispy", and "dark chocolate"), while others are limited in duration or geographic availability. M&M's originated in the United States in 1941, and are now sold in as many as 100 countries.[1] They are produced in different colors, some of which have changed over the years. The candy-coated chocolate concept was inspired by a method used to allow soldiers to carry chocolate without having it melt. The company's longest-lasting slogan reflects this: "Melts in your mouth, not in your hand."