Every retailer with whom we work finds it beneficial to offer promotions from time to time. From free shipping to coupons, promotions can help consumers choose your products over competitors, particularly if they feel they're getting a great bargain in the process.
As with sales tax, promotions are rule-based, meaning that the application and calculation of a promotion are based on rules you create. In Magento, there are two types of promotion rules:
Catalog price rules apply to any product that meets certain criteria. The discount is applied automatically.
Cart price rules, on the other hand, can be set to be only applied when a valid coupon is entered by the customer during checkout. Shopping cart rules can also be applied automatically. Furthermore, shopping cart rules — or coupons — can be publicized by adding them to an RSS feed for your site.