- Reference
The eCommerce Glossary
104 terms, defined the way they are actually used in trading decisions rather than the way they appear in a textbook. Where a term carries a formula or a decision behind it, there is a full page explaining how to calculate it and what to do about the answer.
- Written by the team running the accounts, not generated in bulk
- Each definition says why the term matters, not just what it stands for
- Growing on demand rather than padded to hit a number
A glossary is only useful if the definitions survive contact with a real decision.
- The standard
What a definition has to do to appear here
There is no shortage of eCommerce glossaries. Most are a list of expanded acronyms, which is the least useful part of knowing a term.
The test: could somebody use this definition in a meeting without needing a second source?
Knowing that ROAS stands for return on ad spend helps nobody. Knowing that it can look healthy while a channel loses money, and why, changes what you do on Monday. Every definition here is written to carry that second part.
- What the term means, in one or two sentences
- Why it matters, or the mistake people make with it
- A full page where there is a formula or a decision behind it
- No entries generated in bulk to inflate the count
- New terms added when they earn a place, not on a schedule
We would rather publish 104 terms that are genuinely useful than five hundred that are padding. If a term you need is missing, tell us and we will write it.
- Full definitions
Terms with a page of their own
Where a term has a formula, a benchmark question and a decision attached, one or two sentences is not enough.
Published
Return on ad spend: the formula, a worked example, what a good figure actually depends on, and why it can look healthy on an unprofitable channel.
- Formula and worked example
- Break-even ROAS from your own margin
- Why blended beats platform-reported
Published
Advertising cost of sale on Amazon: how it is calculated, how it relates to TACoS, and how to work out the level your margin can support.
- ACoS, TACoS and the difference
- Break-even ACoS calculation
- What to do when it is too high
Published
AOV: the formula, the three levers that move it, and why raising it can lower profit if you move the wrong one.
- Formula and worked example
- Three ways to move it
- When raising AOV costs you money
In production
Customer acquisition cost
What an order really costs to buy once agency, tool and creative costs are included, and how it relates to lifetime value.
In production — not yet published
In production
Customer lifetime value
Why a lifetime value calculated on revenue is misleading, and how to choose the window it is measured over.
In production — not yet published
In production
Conversion rate
What the number hides when it is blended, and which segments actually tell you something you can act on.
In production — not yet published
More full definitions are written when the shorter entry stops being enough. TACoS, product feed, SKU and marketplace are next.
- A to Z
Every term, alphabetically
Use the letter row to jump. Terms with a full page of their own are linked.
A
8 terms
A/B test
A controlled comparison of two versions of a page or email, where traffic is split and the difference in outcome is measured. Useful only when you have enough traffic to reach a conclusion in a sensible timeframe.
Abandoned cart
A basket a shopper filled and left without buying. The rate is a symptom rather than a problem: the cause is usually a cost, a delivery date or a form that appeared too late.
Advertising cost of sale. Amazon advertising spend divided by the revenue that advertising produced, expressed as a percentage.
A+ Content
Amazon’s enhanced description format for brand-registered sellers, allowing images, comparison modules and richer layout in place of plain text.
Attribution
The set of rules deciding which marketing touchpoint gets credit for a sale. Every model is a simplification, and the disagreement between models is usually larger than people expect.
Revenue divided by the number of orders over the same period. One of the three levers on revenue, alongside traffic and conversion rate.
ASIN
Amazon Standard Identification Number. The ten-character code identifying a product on Amazon, shared by every seller offering that product.
Affiliate marketing
Paying a commission to third parties who send you sales. Cost is variable and tied to outcome, which makes it attractive, but attribution overlap with other channels is a persistent problem.
B
6 terms
Backorder
An order accepted for stock you do not currently hold, to be fulfilled when it arrives. Handled well it protects revenue; handled badly it produces cancellations and support load.
Bounce rate
The share of sessions that end without a second interaction. In eCommerce it is a weak signal on its own, because a satisfied visitor can leave after one page.
Brand Registry
Amazon’s programme for verified brand owners, unlocking enhanced content, additional reporting and tools for reporting listing infringements.
Break-even ROAS
The return on ad spend at which a campaign covers its costs exactly. Calculated from your contribution margin, and the number that tells you whether a ROAS target is ambitious or absurd.
Bundling
Selling several products together at a single price. Raises average order value when the combination makes sense to the shopper and lowers conversion when it does not.
Buy box
The purchase panel on a marketplace product page. On listings with several sellers, only one holds it at a time, and holding it is close to a precondition for selling at all.
C
13 terms
CAC
Customer acquisition cost. Total spend on acquiring customers divided by the number of customers acquired. Blended CAC includes agency, tool and creative costs; most reported figures do not.
Canonical tag
An HTML element naming the preferred version of a page when several URLs show similar content. Wrong canonicals are among the most common and most damaging technical SEO errors.
Cart abandonment rate
The share of created baskets that never became orders. Useful as a trend rather than against a benchmark, because the definition varies between platforms.
Catalogue
The complete set of products, variants and attributes a business sells. Catalogue quality quietly determines search, filtering, advertising and marketplace performance.
Chargeback
A payment reversed by the cardholder’s bank after a dispute. Costs the transaction, the goods and a fee, and a high rate threatens your payment processing.
Churn rate
The share of subscribers or repeat customers lost over a period. In subscription commerce it usually clusters at a specific delivery number rather than spreading evenly.
Click-through rate
Clicks divided by impressions. In search it reflects how well a title and description match intent; in advertising it is a creative and targeting signal rather than a business outcome.
Cohort analysis
Grouping customers by when they first purchased and following each group over time. The clearest way to see whether retention is genuinely improving or the base is just growing.
Contribution margin
What remains from net revenue after cost of goods, fulfilment and marketing. The number that decides whether growth was worth having, and the one most eCommerce reporting omits.
Conversion rate
Orders divided by sessions over the same period. Meaningful segmented by device, channel and landing page; misleading as a single blended figure.
Cost of goods sold
What the products themselves cost you, landed. Excludes marketing and usually excludes fulfilment, which is why gross margin overstates profitability.
Cross-sell
Recommending a complementary product alongside the one being bought. Works when the recommendation is genuinely related and erodes trust when it is filler.
Customer lifetime value
The total contribution a customer produces over the whole relationship. Only useful when calculated on contribution rather than revenue, and on a defined window rather than forever.
D
4 terms
Dayparting
Varying advertising bids or budgets by time of day or day of week. Worth doing where purchase behaviour genuinely varies, and a distraction where it does not.
Dropshipping
Selling products a supplier ships directly to your customer. Low capital requirement, low margin, and you own the customer experience without controlling it.
Dynamic pricing
Adjusting prices automatically in response to demand, competition or stock. Powerful on marketplaces and dangerous without a floor, because repricers race each other downward.
Duplicate content
The same or near-identical text appearing on several URLs, on your site or across retailers. In eCommerce it is usually supplier product copy, and it is why your page has no argument for ranking.
E
4 terms
eCommerce platform
The software your storefront runs on: Shopify, WooCommerce, BigCommerce, Adobe Commerce and others. The choice decides what changes cost and how fast you can trade.
Email flow
An automated sequence triggered by behaviour rather than sent on a date, such as a welcome, browse abandonment or win-back series. Usually outperforms campaign email per send.
Enhanced brand content
A general term for richer product page content on marketplaces, of which Amazon’s A+ Content is the best known example.
Exit rate
The share of sessions that ended on a given page. Useful for finding where a journey breaks, provided you account for pages where leaving is the normal outcome.
F
5 terms
FBA
Fulfilment by Amazon. You send stock to Amazon and they pick, pack, ship and handle returns. Buys Prime eligibility and ties up working capital in their warehouses.
First-party data
Data collected directly from your own customers and site. More durable than third-party data and increasingly the foundation of both targeting and measurement.
Free shipping threshold
The order value above which delivery is free. One of the highest-leverage numbers in eCommerce, and one most stores set once and never revisit against carriage cost.
Fulfilment
Everything between an order being placed and arriving: picking, packing, shipping and returns. Frequently the largest cost line after goods, and frequently absent from marketing reporting.
Product feed
A structured file of your catalogue sent to shopping channels and marketplaces. Feed quality decides what can be advertised and how it is matched to queries.
G
3 terms
Gross margin
Revenue minus cost of goods, as a percentage of revenue. Useful for pricing decisions and insufficient for marketing decisions, because it ignores fulfilment and media.
Google Merchant Center
Where your product feed is submitted for Google Shopping. Feed errors here silently remove products from advertising, often without anyone noticing.
GTIN
Global Trade Item Number, the family of standard product identifiers including EAN and UPC. Required by most shopping channels and marketplaces for product matching.
H
2 terms
Headless commerce
Separating the storefront from the commerce engine, so the front end is built independently. Buys flexibility at the cost of complexity, and is rarely the constraint a store actually has.
Hreflang
Markup telling search engines which language and regional version of a page to serve. Getting it wrong sends the wrong market’s page to your customers.
I
3 terms
Impression share
The proportion of available advertising impressions you actually received. Tells you how much headroom a campaign has before you need new demand rather than more budget.
Incrementality
Whether marketing produced sales that would not have happened anyway. The question attribution cannot answer, and the reason branded search ROAS looks so good.
Inventory turnover
How many times stock is sold and replaced in a period. Low turnover ties up cash and triggers storage costs, particularly in marketplace fulfilment programmes.
K
3 terms
Keyword cannibalisation
Two or more pages competing for the same search intent, so each performs worse than one would. The most common and most expensive error in eCommerce keyword research.
Keyword difficulty
A tool’s estimate of how hard a term is to rank for. Comparable between rows in the same tool and not comparable between tools or against an absolute.
KPI
A measure chosen because a decision depends on it. A number nobody would act on differently is a metric, not a KPI, and reporting it dilutes attention.
L
5 terms
Landing page
The page a visitor arrives on. In eCommerce it is far more often a product or category page than a homepage, which is where most optimisation attention still goes.
Last-click attribution
Giving all credit to the final touchpoint before purchase. Simple, universally understood, and systematically biased toward the channels that close rather than those that create demand.
Lifecycle marketing
Communication mapped to where a customer is in their relationship with you rather than to a campaign calendar. Usually the highest-return email work available.
Listing quality score
Walmart Marketplace’s published measure of listing completeness and quality. Unusually transparent among marketplaces, because it tells you exactly what to fix.
Long-tail keyword
A longer, more specific search phrase with lower volume and usually higher intent. In eCommerce these are frequently where the profitable demand hides.
M
5 terms
MAP pricing
Minimum advertised price. A policy setting the lowest price a reseller may advertise, used to stop a brand’s own channel network racing itself to the bottom.
Marketplace
A platform where multiple sellers list products to a shared audience, such as Amazon, Walmart, eBay, Noon or Shopee. You rent the demand and accept the rules.
Merchandising
Deciding what is shown, where and in what order across categories, search results and recommendations. The commercial craft behind a catalogue rather than a technical function.
MER
Marketing efficiency ratio. Total revenue divided by total marketing spend. Cannot double-count across channels, which is why it is more reliable than summed platform ROAS.
Multi-channel
Selling through more than one route to market, typically your own store plus one or more marketplaces. Multiplies operational load faster than it multiplies revenue.
N
2 terms
Net revenue
Revenue after returns and refunds. The correct starting point for every margin calculation, and routinely replaced by gross revenue in reporting.
Negative keyword
A term you explicitly exclude from advertising. Usually the fastest way to reduce wasted spend on an account nobody has pruned.
O
4 terms
Omnichannel
Operating store, marketplace, social and physical retail as one experience with shared stock and customer data, rather than as separate businesses that share a logo.
Open rate
The share of delivered emails recorded as opened. Increasingly unreliable as a measure since privacy features began pre-loading images, and better treated as a rough trend.
Order management system
The system that takes an order from placement through to fulfilment across channels and warehouses. Becomes necessary at about the point spreadsheets start failing quietly.
Organic traffic
Visitors arriving from unpaid search results. Slower to build than paid traffic and, unlike paid traffic, it does not stop the day you stop spending.
P
7 terms
Payment gateway
The service authorising and processing card payments. Its acceptance rate, supported methods and fees all affect conversion and margin directly.
PDP
Product detail page. Where most eCommerce conversion is decided, and where the largest share of optimisation effort usually should go.
PIM
Product information management. The system holding product attributes, copy and media centrally so every channel reads the same data.
PLP
Product listing page, also called a category or collection page. Carries most commercial search demand and receives the least attention in most stores.
Pre-order
Taking payment or commitment before stock exists. Useful for demand testing and cash flow, and damaging to trust when the promised date slips.
Programmatic advertising
Buying display or video inventory through automated auctions. Rarely the first channel an eCommerce brand should add, and often the first one an agency proposes.
Price parity
Rules requiring your price on one channel to match or better your price elsewhere. Common on marketplaces, and a constraint on pricing strategy rather than a preference.
Q
1 terms
Quality score
An advertising platform’s estimate of how relevant your ad, keyword and landing page are to a query. It affects what you pay per click, so it is a cost lever as well as a quality signal.
R
8 terms
Repeat purchase rate
The share of customers who buy again within a defined window. The single most informative retention number, and the one that decides how much you can afford to acquire.
Replatforming
Moving a store from one eCommerce platform to another. Expensive, disruptive and frequently undertaken to solve a problem the platform was not causing.
Retargeting
Advertising to people who have already visited. Reliable-looking in reporting, because it is shown to people already likely to return, which makes incrementality the real question.
Returns rate
The share of orders or revenue returned. Measure by value rather than by order count, because the expensive returns hide when you count units.
Revenue per session
Revenue divided by sessions. Catches the changes that raise conversion while lowering order value, which conversion rate alone will report as a success.
Rich results
Search results enhanced with price, availability, reviews or images, generated from structured data. Inaccurate markup is worse than none.
Return on ad spend. Revenue attributed to advertising divided by the cost of that advertising.
Robots.txt
A file telling crawlers which parts of a site they may request. A single wrong line here can remove a store from search entirely.
S
7 terms
Schema markup
Structured data added to a page so search engines can interpret products, prices, reviews and breadcrumbs reliably rather than inferring them.
Session
One visit to your site, bounded by inactivity or date. The denominator in conversion rate, and defined slightly differently by every analytics tool.
SKU
Stock keeping unit. Your internal code for one specific sellable variant. Clean SKU discipline underpins inventory, feeds, marketplaces and reporting.
Social commerce
Buying that happens inside a social platform rather than on your own site, including TikTok Shop and in-app checkout. Strong reach, weak customer data.
Structured data
A general term for machine-readable markup describing page content, of which schema.org vocabulary is the standard implementation.
Subscription commerce
Selling on a recurring schedule. Economics depend almost entirely on churn, and churn usually depends on whether the delivery interval matches consumption.
Suppressed listing
A marketplace listing hidden from search because it fails a requirement. Invisible to shoppers, and frequently invisible to the seller until sales drop.
T
5 terms
TACoS
Total advertising cost of sale. Amazon advertising spend divided by total sales including organic, which shows whether advertising is building organic rank or replacing it.
Tag manager
A tool for deploying tracking scripts without a developer. Convenient, and a common cause of slow storefronts when nobody audits what accumulated in it.
Time to first byte
How long the server takes to start responding. A hosting and application measure rather than a front-end one, and a common hidden cause of poor performance scores.
Transaction fee
A charge per sale levied by a platform or marketplace, separate from payment processing. Small individually and significant at volume.
Third-party seller
A seller offering products on a marketplace they do not own. On shared listings, the reason a brand can lose the buy box on its own product.
U
3 terms
Upsell
Offering a higher-value version of the product being considered. Works before the decision is made and irritates after it.
UTM parameter
Tags appended to a URL so analytics can attribute the visit to a campaign. Inconsistent tagging is the most common reason channel reporting cannot be trusted.
Unit economics
What a single order earns and costs, including goods, fulfilment, payment fees and acquisition. If these do not work, scale makes the problem larger rather than smaller.
V
3 terms
Variant
A specific version of a product, such as a size or colour. How variants are structured affects search, feeds, marketplaces and returns.
Sales velocity
How quickly a product sells over a period. On marketplaces it is a major ranking input, which is why launches and stockouts have effects that outlast them.
Voice of customer
Research drawn from what customers actually say: reviews, support tickets, return reasons and surveys. The cheapest conversion research available, and usually unused.
W
2 terms
WFS
Walmart Fulfillment Services. Walmart’s equivalent of FBA, handling storage, pick, pack and returns for marketplace sellers.
Win-back campaign
Communication aimed at customers who have lapsed. Effective when timed to the purchase cycle and wasteful when sent on a fixed schedule long after the decision was made.
Z
1 terms
Zero-party data
Information a customer gives you deliberately, such as preferences or sizing. More reliable than inferred data and increasingly valuable as tracking degrades.
- Going deeper
Where the terms turn into work
A glossary answers what something is. These answer what to do about it.
01
TO ASSESS
Run one against your store to find out which of these terms describes a problem you currently have.
02
TO CALCULATE
Working spreadsheets that compute contribution margin, blended CAC and the rest from your own numbers.
03
TO UNDERSTAND
Chapter-length explanations where a definition is not enough and a full treatment is warranted.
04
TO GET AN ANSWER
We calculate these metrics on your account and tell you which ones are the constraint on growth.
- Related services
The teams these terms belong to
Most of the vocabulary here maps to one of three disciplines.
ROAS, ACoS, CAC, impression share and the rest of the advertising vocabulary, applied to real budgets.
Canonicals, cannibalisation, structured data and the technical terms that decide organic visibility.
Contribution margin, unit economics, inventory turnover and the numbers a business is actually run on.
- Questions
About this glossary
What people ask about how it is built and maintained.
Why only 104 terms?
Because every one is written rather than generated. A glossary of five hundred bulk-produced definitions ranks for a while and helps nobody, and it is exactly the thing search engines have spent several years learning to discount. We add terms when they earn a place.
How do you decide which terms get a full page?
A term gets its own page when there is a formula, a calculation decision or a common misreading attached to it. ROAS earns a page because people act on it incorrectly. Wishlist does not, because knowing what it means is the whole of it.
Can I suggest a term?
Yes, and it is the main way this list grows. Tell us through the contact page which term you were looking for and did not find, and it moves to the top of the queue.
Are the definitions specific to any platform?
Mostly no. Where a term only exists on one platform, such as ASIN, A+ Content, WFS or listing quality score, the definition says so rather than pretending it is universal.
Do you include benchmark figures?
Only where we can source them honestly. Most published eCommerce benchmarks are averages across wildly different categories, price points and traffic mixes, which makes them poor comparisons for any specific business. Where we give a figure, we say where it came from.
How often is this updated?
Terms are revised when practice changes rather than on a schedule. Marketplace terminology moves fastest, because the platforms rename their own programmes regularly.
Can I use these definitions elsewhere?
Quote them, link them, put them in your internal documentation. We would ask that you do not republish the whole list as your own glossary, which helps nobody including you.
Where should I start if all of this is new?
With average order value, conversion rate and contribution margin. Between them they explain most of what a store needs to watch, and the rest of the vocabulary attaches to them.
Know the terms, unsure which one is your problem?
A free eCommerce audit calculates these metrics on your own account and tells you which of them is actually constraining growth, ranked by revenue impact.