A legal certificate offered by manufacturers or retailers that entitles the bearer to a discount on an item at the time of purchase; includes rebates. Alternatively, they can be certificates that give buyers a saving when they purchase a product. A coupon is a very frequent technique in consumer goods marketing. It usually takes the form of a voucher with money off the purchase price, with the purpose of encouraging greater amounts of purchase or else as a way of rewarding consumer loyalty. There is always a vast disparity between the number of coupons issued and the number redeemed, usually in the range of 10–15%, suggesting that this is not a very efficient way of marketing.