Amazon Fulfillment by Amazon (FBA) is a service offered by Amazon that allows sellers to store their products in Amazon's warehouses and have Amazon handle the shipping and customer service for those products.

As a seller, you can earn money by selling your products on Amazon and using the FBA service to fulfill orders. When a customer buys one of your products, Amazon will pick, pack, and ship it to the customer, and also handle customer service for that order. In exchange for this service, Amazon charges a fee for each item that is sold, which includes a storage fee and a fulfillment fee. Sellers can also opt for additional services like Multi-Channel Fulfillment.