M&M's (stylized as m&m's) are multi-colored button-shaped chocolates, each of which has the letter "m" printed in lower case in white on one side, consisting of a candy shell surrounding a filling which varies depending upon the variety of M&M's. The original candy has a semi-sweet chocolate filling which, upon introduction of other variations, was branded as the "plain, normal" 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 (peanut butter, almond, pretzel, crispy, dark chocolate, and caramel) while others are limited in duration or geographic availability. M&M's are the flagship product of the Mars Wrigley Confectionery division of Mars, Incorporated.