Reference
Amazon UK GlossaryEvery term, explained plainly
A working glossary of the Amazon UK terms we use most with clients — from A10 and FNSKU to UKCA marking and TACoS. Written for sellers, not search engines, and kept current with the 2026 UK marketplace standards.
- A10 Algorithm
- Amazon's current search ranking algorithm, prioritising relevance, conversion rate, sales velocity, off-Amazon traffic and seller authority. The successor to A9. Strong listing copy, photography and reviews are the biggest A10 levers. Related service →
- A+ Content
- Enhanced product description modules available to brand-registered sellers and vendors. Replaces the plain product description with image-and-text modules to lift conversion. Premium A+ adds richer modules, video and comparison tables. Related service →
- ACoS (Advertising Cost of Sale)
- Ad spend divided by ad-attributed sales, expressed as a percentage. ACoS measures advertising efficiency on a single campaign. Useful but incomplete on its own — pair with TACoS for the full picture. Related service →
- ASIN (Amazon Standard Identification Number)
- Amazon's unique 10-character product identifier, e.g. B0C1XYZ234. Every product page on Amazon UK has an ASIN. Different variants (size, colour) often share a parent ASIN with child ASINs underneath.
- Backend Search Terms
- Hidden keyword fields in Seller Central used by Amazon's search index. Limited to 250 bytes for the main field. Should contain unique, non-duplicated keywords not already in your title or bullets. Related service →
- Brand Registry
- Amazon's brand-protection programme. Requires a registered trademark. Unlocks A+ Content, Brand Story, Sponsored Brands, the Stores builder and infringement reporting tools. Foundational for any UK private-label seller. Related service →
- Brand Story
- A row of branded modules that appears above A+ Content for Brand-Registered sellers, linking customers to other products in your range and to your Amazon Store. Related service →
- Buy Box (Featured Offer)
- The white panel on a product page where customers click Add to Basket. On listings with multiple sellers, only one offer wins it at a time. Won by the seller with the best blend of price, fulfilment, account health and stock.
- CE Marking / CE-UKNI
- EU conformity mark. Recognised in Northern Ireland (CE-UKNI) and, transitionally, accepted alongside UKCA in Great Britain for many product categories. Confirm category-specific rules before relying on it. Related service →
- CPSR (Cosmetic Product Safety Report)
- A safety dossier required for any cosmetic placed on the UK or EU market, signed by a qualified safety assessor. Amazon may request a copy as part of category gating for cosmetics. Related service →
- Conversion Rate (CVR)
- Sessions that result in a purchase, expressed as a percentage. The single biggest signal A10 uses to decide whether to rank your listing higher. Listing photography, bullets and price all move CVR. Related service →
- FBA (Fulfilment by Amazon)
- You ship inventory to Amazon UK fulfilment centres; Amazon picks, packs, ships and handles returns. Required for Prime eligibility on most listings. Storage and fulfilment fees apply.
- FBM (Fulfilment by Merchant)
- You hold stock and fulfil customer orders yourself (or via 3PL). Lower platform fees but you own logistics, returns and Prime eligibility (via Seller-Fulfilled Prime, where qualifying).
- FNSKU (Fulfilment Network Stock Keeping Unit)
- Amazon's internal barcode for FBA inventory. From 2026, Amazon UK requires every FBA unit to carry an FNSKU label — bare manufacturer barcodes are no longer accepted in most categories. Get this right before sending stock. Related service →
- GTIN / EAN / UPC
- Global Trade Item Number — the umbrella term for product barcodes (EAN-13 in the UK/EU, UPC in the US). Required to create a new ASIN unless you have a GTIN exemption.
- IEN (Importer of Record)
- From 2026 Amazon UK requires the IEN (importer of record name and details) to be declared and traceable on imported goods. Failing to provide IEN data can block listings and shipments. Related service →
- Main Image (Hero Image)
- The primary image shown in search results and at the top of the product page. Must sit on a pure white background (RGB 255,255,255), with the product filling at least 85% of the frame, no props or watermarks. Related service →
- PPC (Pay-Per-Click) Advertising
- Amazon's ad platform — Sponsored Products, Sponsored Brands, Sponsored Display. Listings with weak photography or bullets convert poorly under PPC, wasting budget. Always fix the listing first. Related service →
- Seller Central (3P)
- Amazon's portal for third-party sellers, who own the inventory, the price and the customer relationship. The default route for most UK private-label and reseller brands. Related service →
- TACoS (Total Advertising Cost of Sale)
- Ad spend divided by total sales (organic plus ad-attributed). Falling TACoS while sales rise indicates organic ranking is taking over from paid — usually the goal of a healthy launch. Related service →
- UKCA Marking
- UK Conformity Assessed mark — Great Britain's post-Brexit equivalent of CE for many regulated product categories. Where required, products must be UKCA-marked to be sold lawfully in England, Scotland and Wales. Related service →
- Vendor Central (1P)
- Amazon's invitation-only portal where you sell wholesale to Amazon and Amazon resells to customers. Different economics, chargebacks and PO workflow vs Seller Central. Related service →
- Vine (Amazon Vine)
- A review programme where Brand-Registered sellers offer up to 30 free units to trusted Vine reviewers in exchange for honest reviews. The fastest compliant way to seed reviews on a new ASIN.
Missing a term you'd like us to explain?
Email info@buyboxsavvy.com and we'll add it. We update this glossary as Amazon UK rules change.
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