Pepperoni is an American variety of spicy salami made from cured pork and beef seasoned with paprika and chili peppers. Before cooking, pepperoni is characteristically soft, slightly smoky, and bright red. Sliced pepperoni is one of the most popular pizza toppings in American pizzerias. Traditionally made pepperonis curl into "cups" in the pizza oven's intense heat; commercialization of the production of pepperoni created slices that would lie flat on the pizza. The curled "cup and char" style of pepperoni remained popular in pockets of the Midwest.

Source: Wikipedia