A coupon is a promotional voucher or ticket that provides customers with a discount or rebate on a product or service when presented during a purchase. Coupons are commonly distributed by retailers, both online and offline, as a part of marketing campaigns to attract customers, encourage sales, and foster loyalty. They can come in various forms, including digital codes for online use, printed paper coupons, or mobile app-based discounts. Coupons serve as an effective tool for driving customer engagement, increasing sales, and creating a sense of urgency for consumers to take advantage of special offers or promotions.