Coupon codes are alphanumeric strings that customers can enter at checkout to receive discounts on their purchases. These codes are often provided by retailers as a marketing strategy to attract new customers or encourage repeat business. They can offer various benefits, such as a percentage off the total price, free shipping, or special promotions on specific products. To use a coupon code, shoppers typically enter it in a designated field during the online checkout process. Once applied, the discount is calculated, and the final price is adjusted accordingly. Many websites and apps also aggregate coupon codes, making it easier for consumers to find and use them when shopping online.