E-commerce Glossary: Key Terms & Acronyms Every Seller Should Know

If you're selling on Amazon, Walmart Marketplace, TikTok Shop, or all three and beyond, you've probably hit the same wall: every platform has its own alphabet soup. ACoS, WFS, GMV Max… the acronyms pile up fast, and misreading one can cost you money or momentum.

This glossary breaks down the terms you'll actually run into as a seller. Bookmark it, search it, and use it whenever a new term shows up in a report, a support ticket, or a strategy call.

General E-commerce Terms

These terms apply across marketplaces, no matter where you sell.

SKU (Stock Keeping Unit) is a unique code you assign to a product to track it in your own inventory system. Your SKU is internal (AKA you control the format) while platform-issued identifiers like ASIN or GTIN are how the marketplace tracks the same product externally.

GTIN (Global Trade Item Number) is the umbrella term for standardized product identifiers, including UPCs, that manufacturers use to uniquely identify a product worldwide. Most marketplaces require a GTIN to create a new listing unless you qualify for an exemption.

UPC (Universal Product Code) is the 12-digit barcode number used to identify a specific product for retail sale. You'll need one for most new listings across Amazon, Walmart, and TikTok Shop unless your brand is registered and exempt.

Marketplace is an online platform, like Amazon, Walmart, or TikTok Shop, where multiple third-party sellers list and sell products under one shared storefront. Marketplaces differ from your own direct-to-consumer (DTC) site because the platform controls traffic, search ranking, and much of the customer relationship.

Buy Box is the featured "Add to Cart" or "Buy Now" placement on a product listing, awarded to the seller the platform's algorithm determines offers the best combination of price, fulfillment speed, and seller performance. Winning the buy box is often the single biggest driver of sales on a shared listing, since most shoppers never click past it.

Fulfillment refers to the process of picking, packing, and shipping an order to a customer after it's placed. How you fulfill orders (through the platform, a third party, or in-house) directly affects your shipping speed, cost, and eligibility for premium badges.

3PL (Third-Party Logistics) is an outside company that handles warehousing, packing, and shipping on your behalf instead of the platform or your own team. Sellers use 3PLs to diversify fulfillment beyond a single platform's network, which reduces risk if that network has delays or fee increases.

PPC (Pay-Per-Click) is an advertising model where you pay a fee only when a shopper clicks your ad, rather than for impressions or placements alone. PPC is the foundation of nearly every marketplace ad program, including Amazon Ads, Walmart Connect, and TikTok Shop Ads.

CPC (Cost-Per-Click) is the actual amount you pay each time a shopper clicks one of your ads. Your CPC is shaped by keyword competition, your bid, and your listing's relevance and performance.

CTR (Click-Through Rate) is the percentage of people who click your ad or listing after seeing it, calculated by dividing clicks by impressions. A low CTR usually points to a weak main image, price, or title relative to the competition — not necessarily a bad product.

CVR (Conversion Rate) is the percentage of shoppers who make a purchase after clicking your listing or ad. Improving CVR, through better images, reviews, or pricing, often delivers a faster return than simply driving more traffic.

ROAS (Return on Ad Spend) is the amount of revenue you generate for every dollar spent on advertising, expressed as a ratio. A 4x ROAS means every $1 in ad spend generated $4 in sales — but ROAS alone doesn't account for product cost, so it should be read alongside your margins.

AOV (Average Order Value) is the average dollar amount a customer spends per order, calculated by dividing total revenue by total number of orders. Raising AOV, through bundles or upsells, is often more cost-effective than acquiring new customers.

CAC (Customer Acquisition Cost) is the total marketing and advertising cost required to acquire one new customer. Comparing CAC to customer lifetime value tells you whether your growth is actually profitable or just expensive.

GMV (Gross Merchandise Value) is the total dollar value of all goods sold through a platform or seller account over a given period, before fees, returns, and expenses are deducted. GMV is a scale metric, not a profit metric — a high GMV doesn't guarantee healthy margins.

Chargeback is a fee a marketplace deducts from a seller for failing to meet a specific operational requirement, such as a compliance or labeling error. Chargebacks are different from returns; they're penalties tied to process failures, not customer dissatisfaction.

MAP (Minimum Advertised Price) is the lowest price a brand allows retailers and sellers to publicly advertise a product for, regardless of the actual sale price. Enforcing MAP protects brand value and prevents a race to the bottom across multiple sellers of the same product.

Landed Cost is the total cost to get a unit of inventory ready to sell, including the product cost, freight, duties, and any prep or storage fees. Pricing off landed cost, instead of just the manufacturing cost, is what keeps margins accurate.

Inventory Turnover is a measure of how many times you sell through and replace your inventory over a given period. Low turnover often signals overstock and rising storage fees; high turnover can signal stockout risk if you're not reordering fast enough.

Omnichannel describes a selling strategy that connects multiple sales channels, such as a brand's own site, Amazon, Walmart, and TikTok Shop, into one coordinated customer experience. An omnichannel approach spreads platform risk and captures shoppers wherever they already browse.

Amazon-Specific Terms

Seller Central is the dashboard third-party sellers use to manage listings, inventory, advertising, and performance on Amazon. It's the operational home base for anyone selling under the third-party model, as opposed to selling directly to Amazon.

Vendor Central is the portal used by brands that sell wholesale directly to Amazon, which then resells the product to customers as the retailer of record. Vendor Central and Seller Central represent two fundamentally different relationships with Amazon — one sells to Amazon, the other sells on Amazon.

FBA (Fulfilled by Amazon) is a fulfillment method where you send inventory to Amazon's warehouses and Amazon handles storage, packing, shipping, and customer service for those orders. FBA products are typically eligible for Prime shipping, which can meaningfully boost conversion.

FBM (Fulfilled by Merchant) is a fulfillment method where you store, pack, and ship orders yourself instead of relying on Amazon's warehouses. FBM gives sellers more control over inventory and cost but requires meeting Amazon's shipping speed and service standards on your own.

SFP (Seller Fulfilled Prime) is a program that lets you fulfill orders yourself while still displaying the Prime badge, provided you meet Amazon's fast, reliable shipping requirements. SFP requires an invitation and consistent performance, since a single missed shipment can affect eligibility.

ASIN (Amazon Standard Identification Number) is the unique code Amazon assigns to every product listed on its platform. Every variation of a product, such as different sizes or colors, typically gets its own ASIN.

FNSKU (Fulfillment Network Stock Keeping Unit) is the barcode Amazon requires on FBA units so its fulfillment centers can identify and track your specific inventory. Without a correctly applied FNSKU label, FBA inventory can be commingled with other sellers' stock or rejected at receiving.

Brand Registry is an Amazon program that verifies your trademark and unlocks brand protection tools, enhanced content, and reporting. Getting Brand Registered is one of the highest-leverage moves a brand can make on Amazon, since it also opens access to A+ Content and Amazon Ads' full suite.

A+ Content is enhanced product description content, featuring custom images and layouts, available to Brand Registered sellers. Listings with A+ Content typically see stronger conversion rates because they answer shopper questions visually instead of through plain text.

Amazon Ads is Amazon's advertising program, encompassing Sponsored Products, Sponsored Brands, Sponsored Display, and its demand-side platform (DSP). Amazon Ads spans on-platform and off-platform placements, giving sellers reach well beyond the search results page.

ACoS (Advertising Cost of Sale) is the percentage of ad-attributed sales spent on advertising for a specific campaign, calculated by dividing ad spend by ad-attributed revenue. A lower ACoS means more efficient ad spend, but the "right" ACoS depends on your margin and growth goals.

TACoS (Total Advertising Cost of Sale) is the percentage of your total sales, both organic and ad-driven, spent on advertising. Where ACoS measures campaign efficiency, TACoS shows whether your ad spend is actually growing your overall business.

DSP (Demand-Side Platform) is Amazon's programmatic advertising tool for buying display, video, and audio ads both on and off Amazon, targeting shoppers using Amazon's first-party data. DSP is generally used for upper-funnel brand awareness rather than direct-response sales.

IPI (Inventory Performance Index) is Amazon's score, from 0–1,000, that measures how efficiently you manage FBA inventory. A low IPI score can trigger storage limits, so sellers should monitor excess inventory and sell-through rate closely.

LTSF (Long-Term Storage Fee) is an additional charge Amazon applies to FBA inventory that's been sitting in a fulfillment center for an extended period, typically over a year. LTSFs are one of the fastest ways slow-moving inventory erodes margin, which makes IPI management directly tied to profitability.

Vine is an Amazon program that provides free products to trusted reviewers in exchange for honest reviews, helping new listings build early social proof. Vine reviews are clearly labeled and can't be incentivized beyond the free product itself.

Walmart Marketplace-Specific Terms

Seller Center is Walmart's version of Seller Central, the dashboard sellers use to manage listings, orders, and advertising on Walmart Marketplace. The naming is easy to mix up with Amazon's "Seller Central," but the platforms and requirements are distinct.

WFS (Walmart Fulfillment Services) is Walmart's version of FBA, where Walmart stores, packs, and ships your inventory from its own fulfillment network. WFS items are eligible for two-day shipping badges, which can meaningfully improve visibility in Walmart search results.

Walmart Connect is Walmart's retail media and advertising platform, covering sponsored search ads, display ads, and off-site placements. Walmart Connect functions much like Amazon Ads but leans on Walmart's in-store and omnichannel shopper data as a differentiator.

Item Spec refers to the required and optional data fields Walmart uses to set up and categorize a product listing correctly. Incomplete or inaccurate item specs are one of the most common reasons a Walmart listing gets suppressed or rejected.

Pro Seller Badge is a trust indicator Walmart awards to sellers who consistently meet performance benchmarks around shipping, cancellations, and customer service. The badge signals reliability to shoppers and can influence buy box eligibility.

Trust Score is Walmart's internal rating of a seller's overall account health, based on factors like order defect rate, on-time shipping, and valid tracking rate. A declining Trust Score puts buy box eligibility and account standing at risk, similar to Amazon's account health metrics.

Repricer is a tool, either Walmart's built-in feature or a third-party solution, that automatically adjusts your product price based on competitor pricing and buy box rules. Repricing is especially important on Walmart, since price competitiveness carries significant weight in its buy box algorithm.

TikTok Shop-Specific Terms

GMV Max is a TikTok Shop automated advertising solution that combines organic content, paid ads, and affiliate promotion into a single campaign optimized toward maximizing gross merchandise value. Sellers set a budget and goal, and TikTok's algorithm handles targeting and placement across formats.

LIVE Shopping is real-time selling through a livestream, where hosts demonstrate products and viewers can purchase directly without leaving the stream. LIVE Shopping is one of TikTok Shop's core differentiators and often drives significantly higher engagement than static listings.

Shoppable Video is short-form video content with an embedded product link or shopping tag, allowing viewers to purchase without leaving the app. Shoppable video blurs the line between content and commerce, which is central to how TikTok Shop drives discovery-based buying.

Creator Marketplace is TikTok's platform for connecting sellers with content creators and affiliates who promote products in exchange for a commission. Running an affiliate program through the Creator Marketplace is one of the fastest ways to generate authentic, high-volume content for a new product.

VSA (Video Shopping Ads) is a TikTok Shop ad format that boosts existing shoppable video content into users' feeds to drive product discovery and purchases. VSAs let sellers pay to amplify content that's already performing well organically, rather than building a separate ad creative from scratch.

Sample Program is a TikTok Shop feature that lets sellers send free product samples to creators in exchange for content, without a guaranteed sale. It's typically the fastest, lowest-cost way for a new seller to build a base of creator content and reviews.

Shop Tab is the dedicated shopping section within the TikTok app where users can browse and purchase products directly, separate from the main content feed. The Shop Tab functions as TikTok's answer to a traditional marketplace storefront, alongside its video-driven discovery.

Meta Ads-Specific Terms

Meta Ads Manager is the dashboard used to build, run, and report on ads across Facebook and Instagram. It's the operational hub for sellers running off-platform traffic into their Amazon, Walmart, TikTok Shop, or direct-to-consumer (DTC) listings.

Pixel is a snippet of code placed on a website that tracks visitor behavior and reports it back to Meta for ad targeting and measurement. The pixel has been increasingly supplemented, and in some cases replaced, by server-side tracking as browser privacy restrictions limit what it can see on its own.

CAPI (Conversions API) is a server-side tracking method that sends conversion data directly from a seller's server to Meta, rather than relying solely on browser-based tracking like the pixel. CAPI has become essential for accurate attribution since iOS privacy changes reduced how much data the pixel alone can capture.

Advantage+ Shopping Campaigns is Meta's automated campaign type that uses machine learning to handle targeting, placements, and creative optimization for e-commerce advertisers with minimal manual input. Sellers running Advantage+ typically provide a product catalog and budget, then let Meta's algorithm manage most of the targeting decisions.

Lookalike Audience is a Meta targeting option that finds new users who share characteristics with an existing customer list or website audience. Lookalikes are commonly used to scale beyond a brand's core retargeting pool once that pool becomes too small to grow further.

Catalog Sales is a Meta ad objective that pulls product data from a connected catalog to dynamically generate ads showing the specific items a user viewed or is likely to want. Catalog Sales campaigns power dynamic retargeting, so an abandoned-cart shopper can see the exact product they left behind.

Dynamic Creative is a Meta ad feature that automatically tests combinations of images, headlines, and copy to identify which version performs best for a given audience. Rather than guessing which creative will win, Dynamic Creative lets the algorithm surface the top-performing combination through live testing.

Attribution Window is the timeframe during which Meta credits a conversion to an ad click or view. A shorter attribution window, such as one day, gives a more conservative read on performance than a longer one, such as seven days, which can make campaigns look stronger than they are on a pure last-click basis.

Google Ads-Specific Terms

Google Ads Manager is the interface advertisers use to build, run, and report on campaigns across Google Search, Shopping, Display, and YouTube. For e-commerce sellers, it's typically where Shopping campaigns and Performance Max campaigns live.

Google Merchant Center is the platform where sellers upload and manage their product feed, including titles, images, and pricing, so those products can appear in Shopping ads and free listings. A rejected or suspended Merchant Center feed will stop Shopping ads from running entirely, so feed health should be monitored closely.

Shopping Ads are product-based ads, pulled directly from a Merchant Center feed, that show a product image, price, and store name in Google search results. Shopping Ads convert differently than traditional text ads because the shopper sees price and product before ever clicking.

PMax (Performance Max) is a Google Ads campaign type that uses automation to place ads across Search, Shopping, Display, YouTube, and Gmail from a single campaign. PMax trades granular channel-by-channel control for broader automated reach, which makes clear goals and quality inputs, like feed data and creative assets, especially important.

Smart Bidding is Google's umbrella term for automated bidding strategies, such as Target ROAS and Target CPA, that use machine learning to set bids in real time based on the likelihood of a conversion. Smart Bidding generally needs a meaningful volume of historical conversion data to perform well, so newer accounts may see inconsistent results early on.

tROAS (Target Return on Ad Spend) is a Smart Bidding strategy where you set a target revenue-to-spend ratio and Google's algorithm adjusts bids to try to hit it. Setting a tROAS goal too aggressively can restrict how much volume the algorithm is willing to spend into, even if the product could support more traffic profitably.

tCPA (Target Cost Per Acquisition) is a Smart Bidding strategy where you set a target cost per conversion and Google adjusts bids to try to hit that average. tCPA is often used for lead generation or lower-funnel goals, while tROAS is more common for e-commerce, since it accounts for order value rather than a flat per-conversion cost.

Quality Score is Google's 1–10 rating of an ad's expected relevance and performance, based on expected click-through rate, ad relevance, and landing page experience. A higher Quality Score typically lowers your cost-per-click for the same ad position, which makes it a direct lever on ad efficiency, not just a vanity metric.

Impression Share is the percentage of eligible impressions your ads actually received, compared to the total available for your targeting. A low impression share due to budget, rather than rank, usually signals room to spend more profitably before hitting diminishing returns.

GA4 (Google Analytics 4) is Google's analytics platform for tracking website traffic, conversions, and customer behavior across devices and channels. GA4 uses an event-based data model, a significant shift from its predecessor, which makes accurate setup critical for reliable Google Ads reporting and attribution.

Keep This Glossary Handy

New terms show up on every platform every year, and the acronyms rarely explain themselves. When in doubt, remember the pattern: general e-commerce metrics like CTR, CVR, and ROAS travel across every platform, while fulfillment programs (FBA, WFS), advertising platforms (Amazon Ads, Walmart Connect, TikTok Shop Ads), and seller dashboards (Seller Central, Seller Center, TikTok Shop Seller Center) are where each marketplace goes its own way.

Selling across Amazon, Walmart, and TikTok Shop means speaking three dialects of the same language. The faster you're fluent, the faster you can act on what your data is actually telling you.