M&M's are small, colorful chocolate candies that have a hard candy shell. They were first introduced in 1941 and are produced by Mars, Incorporated. Each candy is typically marked with the letter "M" printed on one side. M&M's come in various flavors, including milk chocolate, peanut, almond, and crispy. The candies are popular for their fun colors and are often used in baking, decorating, or as snacks. M&M's are also known for their catchy advertising campaigns and mascots, which have contributed to their status as a beloved treat worldwide.