Prizes are promotional items—small toys, games, trading cards, collectables, and other small items of nominal value—found in packages of brand-name retail products (or available from the retailer at the time of purchase) that are included in the price of the product (at no extra cost) with the intent to boost sales. Collectable prizes produced (and sometimes numbered) in series are used extensively—as a loyalty marketing program—in food, drink, and other retail products to increase sales through repeat purchases from collectors. Prizes have been distributed through bread, candy, cereal, chips, crackers, laundry detergent, margarine, popcorn, and soft drinks. The types of prizes have included comics, fortunes, jokes, key rings, magic tricks, models (made of paper or plastic), pin-back buttons, plastic mini-spoons, puzzles, riddles, stickers, temporary tattoos, tazos, trade cards, trading cards, and small toys (made from injection molded plastic, paper, cardboard, tin litho, ceramics, or pot metal). Prizes are sometimes referred to as "in-pack" premiums, although historically the word "premium" has been used to denote (as opposed to a prize) an item that is not packaged with the product and requires a proof of purchase and/or a small additional payment to cover shipping and/or handling charges.