I don't think I need to define what a "coupon" is... as consumers we have all used or come across coupons in the past. We cut them out and use them to save money on products we buy - quite simple.
However, manufacturers can leverage coupons for variety of different strategic marketing objectives:
Coupons are frequently used by manufacturers because of competitive pressure. When used offensively against the competition, coupons are issued to get users of a competitive product to try a new brand. When used defensively, manufacturers provide coupons to current users to keep them from purchasing a competing brand. More and more coupons are also being used in conjunction with mobile technology.
The process of planning, creating, distributing coupons can be quite complex and involves several parties. See below the typical process of a coupon that is distributed in conjunction with a retailer and for which the redemption is accepted at retailers and handled by a clearing house, as opposed to direct marketing coupons that are distributed and accepted by the manufacturer only (with redemption handled directly by the manufacturer).

SAP CRM Marketing supports companies throughout the process by providing:
To show you, I have created a short video that outlines the following elements:
1) Coupon campaign creation - including key information for coupon tracking and printing.
2) Coupon cost planning and redemption prediction
3) Coupon campaign execution and collaboration with a clearinghouse.
Let me know if you have any questions.