Amazon Seller Glossary

Clear, practical definitions of the terms Amazon sellers use every day, from ASIN to AI agents.

ASIN: Amazon Standard Identification Number. A unique 10-character code Amazon assigns to each product in its catalog. Each marketplace may use the same ASIN for the same product, and every listing, offer and review is tied to it.

SKU: Stock Keeping Unit. An identifier the seller assigns to track each product in inventory. One ASIN can have multiple seller SKUs, for example to separate FBA and FBM offers or different conditions.

FBA: Fulfillment by Amazon. A program in which sellers send inventory to Amazon fulfillment centers, and Amazon handles storage, picking, packing, shipping, customer service and returns. FBA offers are typically Prime-eligible.

FBM: Fulfilled by Merchant. A model in which the seller stores inventory and ships orders directly or through a third-party logistics provider. It offers more control and can suit bulky, slow-moving or temperature-controlled items.

SP-API: Selling Partner API. Amazon’s official API that lets authorized applications access seller data such as orders, inventory, listings, pricing and reports. KeyCenter connects to your account through SP-API with your explicit authorization.

Buy Box: The “Add to Cart” section on a product page. When several sellers offer the same product, Amazon chooses which offer wins the Buy Box based on factors such as price, availability, fulfillment method and seller performance.

ACoS: Advertising Cost of Sales. Ad spend divided by ad-attributed sales, expressed as a percentage. A lower ACoS means more efficient advertising, but the right target depends on your margins and growth goals.

TACoS: Total Advertising Cost of Sales. Ad spend divided by total sales, including organic sales. TACoS shows how advertising affects your overall business and whether ads are helping build organic ranking over time.

ROAS: Return on Ad Spend. Ad-attributed sales divided by ad spend, the inverse of ACoS. For example, a ROAS of 4 means four units of revenue were generated for every unit spent on advertising.

BSR: Best Sellers Rank. A ranking that reflects a product’s recent sales performance within its category. It is updated frequently and is widely used as an indicator of sales velocity and competition.

Brand Registry: Amazon’s program for brand owners with a registered or pending trademark. It provides tools such as A+ Content, Sponsored Brands, brand analytics and stronger protection against counterfeit or inaccurate listings.

A+ Content: Enhanced product descriptions available to brand-registered sellers, featuring rich images, comparison charts and structured text modules. Well-designed A+ Content can improve conversion and reduce returns by setting clear expectations before purchase.

Sponsored Products: Amazon’s cost-per-click ad format that promotes individual product listings in search results and on product pages. It is usually the foundation of an Amazon advertising strategy and can be run with automatic or manual targeting.

Sponsored Brands: Ads that feature your brand logo, a custom headline and multiple products or a video, typically shown at the top of search results. They are available to brand-registered sellers and help build brand awareness.

Sponsored Display: A display advertising format that reaches shoppers on and off Amazon based on interests, viewing behavior or product targeting. It is often used for retargeting and for defending your own product detail pages.

IPI Score: Inventory Performance Index. A score Amazon uses to measure how efficiently a seller manages FBA inventory, considering factors such as excess stock, sell-through and in-stock rates. It can influence storage limits.

Long-term Storage Fee: An additional fee Amazon charges for FBA inventory stored beyond a certain period. It encourages sellers to keep inventory moving and is a major reason to forecast accurately and clear slow-moving stock in time.

Inventory Turnover: How many times inventory is sold and replaced over a given period. Higher turnover generally means capital is used efficiently and storage costs are lower, while very high turnover may signal risk of stockouts.

Lead Time: The time between placing a purchase order and the inventory becoming available for sale, including production, shipping, customs and FBA check-in. Accurate lead times are essential for setting reorder points.

Safety Stock: Extra inventory held to protect against unexpected demand spikes or supply delays. The right amount balances the cost of holding stock against the cost of lost sales and ranking from stockouts.

Reorder Point: The inventory level at which a new purchase order should be placed. It is typically calculated from average daily demand multiplied by lead time, plus safety stock, so new stock arrives before running out.

Demand Forecasting: Estimating future sales using historical data, seasonality, promotions, pricing and market trends. AI-based forecasting can model many variables at once and update predictions continuously as new sales and market data arrive.

Repricing: Automatically adjusting product prices in response to competitors, demand and inventory levels. Good repricing protects margins with floor and ceiling rules rather than simply matching the lowest price on every change.

JAN/GTIN: Global Trade Item Number, the family of product barcodes that includes UPC and EAN. JAN is the Japanese version of the EAN code. Amazon generally requires a valid GTIN to create new product listings unless an exemption applies.

Account Health: Amazon’s overview of a seller’s compliance with performance targets and policies, including order defect rate, late shipments and policy violations. Poor account health can lead to listing removals or account suspension.

Pan-European FBA: An FBA program that lets sellers send inventory to one European country while Amazon distributes it across EU fulfillment centers closer to customers. It can speed delivery but may create VAT obligations in multiple countries.

Remote Fulfillment: An Amazon program that lets sellers use FBA inventory stored in one country to fulfill orders from customers in other participating marketplaces. It allows testing new markets without shipping inventory abroad.

Multi-Channel Fulfillment: An Amazon service that fulfills orders from other sales channels, such as your own website or other marketplaces, using your FBA inventory. It helps centralize stock and simplify logistics across channels.

Listing Optimization: Improving titles, bullet points, descriptions, images, backend keywords and attributes to increase search visibility and conversion. It is an ongoing process that should respond to search trends and customer feedback.

AI Agent: Software that uses artificial intelligence to monitor data, make decisions and take actions toward defined goals with limited human input. KeyCenter AI agents automate Amazon operations within rules and approval steps you control.

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