Sprinkles are tiny pieces of confectionery. They can be made out of sugar or (dark, milk, etc.) chocolate, are really colorful, and are used to decorate desserts, like cakes and pastries.
You can buy them in supermarkets or in stores specialized in partymaking, in single-color packages, or else in mixed packages. They are quite similar to nanpareils, whic are tiny tiny balls made with sugar and starch.
Among recipes with Sprinkles, there are chocolate truffles and Italian struffoli.