What is the best selling candy bar in the world based on global sales as of 2013?

Snickers holds the top spot for the biggest selling candy bar in the world. Made by Mars, Incorporated, Snickers has annual global sales of 2 billion dollars. The bar consists of nougat topped with caramel and peanuts covered in milk chocolate. It was named after Mars family's favorite horse when it was introduced in 1942.

According to Wikipedia, the bar was marketed under the name "Marathon" in the UK and Ireland until July 19, 1990, when Mars decided to align the UK product with the global Snickers name (Mars had marketed and discontinued an unrelated bar named Marathon in the United States during the 1970s). There are also several other Snickers products such as Snickers mini, dark chocolate, ice cream bars, Snickers with almonds, Snickers with hazelnuts, Snickers peanut butter bars and Snickers with Extra Caramel.