Marketplace
What is Buy Box?
The add-to-cart button on an Amazon product page when more than one seller offers the same item. Winning it means your offer is the default one shoppers buy, decided by price, fulfillment, and seller performance.
Why it matters in practice
Almost nobody scrolls to the other offers, so losing the Buy Box on a page you still technically appear on behaves a lot like being delisted. Sales can fall off a cliff with no listing change, no ranking change and no obvious cause, which is why the first question when revenue drops for no reason should be whether the offer is still the default one. Price matters but is not the whole story: fulfillment speed and seller performance are weighed too, which is how a slightly higher priced offer can hold it. The useful habit is to stop treating it as won or lost and start watching the share of the day you held it, because a page you hold most of the time and lose every evening is a very different problem from one you never win at all.
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