The Power of Up-Selling.. by Anthony L. Davenport --------------------------------------------- Before I get into how Up-Selling can benefit you and your sales, let me answer the question: What is an Up-sell? An up sell is when a customer is ready to order a product, or already has ordered a product from you, then you immediately offer a complimentary product. This is the most common example of a perfect upsell: You go into your local fast food restaurant , (Burger King, McDonalds, etc.).