Amazon

Amazon is the largest general e-commerce marketplace in the world, combining first-party retail with a third-party marketplace that now accounts for the majority of units sold.

Its operational advantage is FBA: sellers ship inventory into Amazon's warehouses and the platform handles storage, delivery and returns, which is what makes Prime delivery speeds possible across such a wide catalogue.

For sellers the trade-off is dependence — ranking, buy-box allocation and account standing are controlled by the platform, and category rules and fees change without negotiation. Most experienced sellers treat it as one channel rather than the only one.