Fulfillment by Amazon or FBA is a service offered by Amazon for third-party sellers with the intent to automate their shipping services and order fulfillment process. It's an easy and hassle-free concept: Sellers sell, Amazon fulfills, and ships. If sellers enroll for FBA, then Amazon handles shipping, product warehousing, and returns and refunds for them. Moreover, Amazon also takes care of the picking, packing, and replacing of the sellers who take the FBA service. In this service, all sellers have to do is send their products to Amazon, which then processes all the orders that come in. Sellers need to ensure that Amazon has a good stock of their products and that the rest is taken care of.