The Complete Glossary of Amazon & Cross-Border Ecommerce Terms
Selling on Amazon USA from overseas comes with a wall of acronyms, from FNSKU to IPI to Form 5472. This glossary defines the terms that actually matter for a cross-border seller, in plain language, in one place. Bookmark it, share it with your team, or link to it when you need a clean definition.
One reference for the Amazon and cross-border terms sellers meet most: fulfillment, fees, inventory health, compliance and import vocabulary, each defined in a sentence or two.
What's in this guide
Fulfillment and inventory
FBA (Fulfillment by Amazon): Amazon stores your inventory, then picks, packs and ships orders and handles customer service.
FBM (Fulfillment by Merchant): you store and ship orders yourself or through a third party rather than Amazon.
3PL (Third-Party Logistics): a company that stores and ships inventory on your behalf, often used to hold buffer stock outside FBA.
Prep: preparing units to Amazon's standards, including labeling, poly-bagging and bundling, which since 2026 must be done before inventory reaches FBA.
Buffer stock: reserve inventory held in a cheaper warehouse and fed into FBA in small batches to avoid storage penalties.
Drip-feeding: the practice of sending FBA only a few weeks of stock at a time, matched to sales velocity.
AWD (Amazon Warehousing and Distribution): Amazon's own bulk-storage service that replenishes FBA.
MCF (Multi-Channel Fulfillment): using FBA inventory to fulfill orders from other sales channels.
Fees and inventory health
Referral fee: the commission Amazon takes on each sale, varying by category.
Fulfillment fee: the per-unit charge for FBA picking, packing and shipping.
Storage fee: the monthly charge for space your inventory occupies in FBA, which rises sharply in Q4.
Aged-inventory surcharge: an extra fee on stock that sits in FBA too long, starting at 181 days in 2026.
IPI (Inventory Performance Index): Amazon's score for how efficiently you use FBA; a low score can trigger storage limits.
Restock limits: caps on how much inventory you can send to FBA, influenced by your IPI and sales.
Listings and identifiers
ASIN (Amazon Standard Identification Number): the unique ID Amazon assigns to each product listing.
SKU (Stock Keeping Unit): your own internal code for a product.
FNSKU (Fulfillment Network SKU): the barcode Amazon uses to track your specific units in its network.
Buy Box: the featured offer that wins the add-to-cart button on a listing.
Brand Registry: Amazon's program for trademark owners that unlocks brand protection and content tools.
Listing: the product page where your item is sold.
Compliance and tax
LLC (Limited Liability Company): a common US business structure for foreign sellers.
EIN (Employer Identification Number): the federal tax ID for a US business, obtainable without an SSN.
Form 5472: a federal information return most foreign-owned US LLCs must file, with a $25,000 penalty for missing it.
Marketplace facilitator: a marketplace legally required to collect and remit sales tax for its sellers in most states.
Nexus: a connection to a US state, such as storing inventory there, that can create tax obligations.
Prop 65: a California law requiring chemical-exposure warnings that can reach nationwide listings.
Import and logistics
HS code (Harmonized System code): the international classification number that determines import duty on your product.
Customs broker: a licensed agent who clears your shipment through US customs.
Duty: the tax charged on imported goods, based on HS code and value.
Freight forwarder: a company that arranges the movement of goods from origin to destination.
Air vs sea freight: the two main import modes, trading speed against cost.
Country of origin: where goods are made, which must be accurately declared and often labeled.
Keep this glossary handy as you scale, and feel free to link to it as a reference for your own readers or team.