AMAZON 的說明如下

Share the Love

Each time you place an order for books, music, DVDs, or videos with us, we'll offer you the chance to e-mail your friends and give them an additional 10% off the items you bought. (You select which items, of course.) If any of those people purchases one of those items within a week, you'll receive a credit to use the next time you shop with us! Your credit will equal the dollar amount of your friend's 10% discount. Let's say you bought a CD for $15 and decided to Share the Love with a friend on that purchase. Your friend would be able to buy the same CD for $13.50. You would receive a credit for $1.50 (the difference) to use any time in the next 30 days. You are eligible to receive one credit per item shared.

資料來源:
http://www.amazon.com