There are mainly 3 kinds of vouchers available at most shops, both online and offline. The first type provides a particular percentage of discounts on your expense rate. When the rate is a huge quantity, this type is much better redeemed. The second type is that which provides a particular quantity as the discount worth. This makes more sense for low expense purchases. The 3rd and maybe the most complicated range is the one that states things like 'buy one, get one free'. The discount would be the same when the discount coupon states 'buy one, get 2',