The "Buy Box" is the box on a product detail page where customers start the purchase process by adding items to their shopping carts.
A key feature of the Amazon platform is that the same product can be sold by multiple sellers. If several sellers offer the same product in "New" condition, they may compete for the Buy Box for that product.
Sellers must qualify for Featured Merchant status in order to compete for Buy Box placement. Featured Merchant status is tied to specific seller performance criteria that determine the sellers who have consistently provided customers with a great buying experience on the Amazon.com site.