Fulfillment by Amazon (FBA) is a service provided by Amazon that allows third-party sellers to store their products in Amazon's fulfillment centers. When a customer places an order for a seller's product, Amazon will pick, pack, and ship the product to the customer on behalf of the seller. Amazon also handles customer service and returns for FBA products.

FBA provides several benefits for sellers, including access to Amazon's vast customer base, access to Amazon Prime customers, and increased visibility in search results. Additionally, FBA products are eligible for Amazon's Two-Day Shipping and other Prime benefits, which can improve sales and customer satisfaction.

FBA also helps sellers save time and money on shipping and logistics. Amazon's fulfillment centers are strategically located around the world, which can help sellers reduce shipping costs and delivery times. Amazon also provides inventory management and storage services, which can free up sellers' time to focus on other aspects of their business.

Overall, FBA is a popular and effective way for third-party sellers to leverage Amazon's infrastructure and customer base to grow their business and improve their bottom line.