Glossary

54 terms, defined without the hand-waving.

Every entry opens with a single self-contained sentence, then says the thing the definition alone leaves out. No figures here — anything numeric belongs in an article where it can carry a source.

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Unit economics11
Measurement & attribution13
Channels & buying9
Creative & conversion7
Lifecycle & retention5
Search & AI search9

Unit economics

Blended CAC: Blended customer acquisition cost is total acquisition spend across every channel divided by total new customers, regardless of which channel gets the credit.; Its value is precisely that it ignores attribution. When platform-reported numbers disagree, blended CAC is the figure the bank account agrees with.; SeeCustomer acquisition cost,Marketing efficiency ratio
Cohort analysis: Cohort analysis groups customers by when or how they were acquired and tracks each group's behaviour over time, rather than averaging all customers together.; It is the only way to see whether newer customers are behaving worse than older ones — a deterioration that a blended average hides completely.; SeeLifetime value,Retention rate
Contribution margin: Contribution margin is revenue minus the variable costs of delivering it, before fixed overhead.; It sets the ceiling on what can be paid to acquire a customer. Acquisition planning that ignores it optimises toward growth that loses money per unit.; SeePayback period,Lifetime value
Cost per acquisitionCPA: Cost per acquisition is the advertising cost of generating one defined conversion event, which may be a sale, a lead, an install or any other chosen action.; The term is only meaningful once the conversion event is named. A CPA on form fills and a CPA on closed revenue describe different worlds.; SeeCustomer acquisition cost,Cost per lead
Cost per leadCPL: Cost per lead is the advertising cost of generating one enquiry, before any judgement about whether that enquiry is worth working.; Trivially improved by making the lead worse. Cost per accepted lead is the version that tracks revenue.; SeeAccepted lead,Cost per acquisition
Customer acquisition costCAC: Customer acquisition cost is the total cost of acquiring one new customer, calculated by dividing all acquisition spend in a period by the number of new customers gained in that period.; Whether it includes salaries, agency fees and creative production changes the number substantially. Agree the inclusions before comparing it to anything.; SeeBlended CAC,Payback period,Lifetime value
Lifetime valueLTV or CLV: Lifetime value is the total contribution margin a customer is expected to generate across their entire relationship with a business.; In categories with skewed value distributions, the mean is dominated by a small tail. A conservative percentile is a safer basis for setting acquisition budget.; SeeContribution margin,Cohort analysis
LTV:CAC ratio: The LTV:CAC ratio compares expected lifetime value against the cost of acquisition, expressing how many times over a customer repays what they cost to win.; It says nothing about timing. A healthy ratio with a long payback period can still starve a business of working capital.; SeeLifetime value,Payback period
Marketing efficiency ratioMER: Marketing efficiency ratio is total revenue divided by total advertising spend over the same period, measured across the whole business rather than per campaign.; Unlike return on ad spend, it cannot be inflated by attribution choices, because both numbers come from your own accounts.; SeeReturn on ad spend,Blended CAC
Payback period: Payback period is the time it takes for the contribution margin from a customer to equal what it cost to acquire them.; It governs how fast a business can grow without external funding. A shorter payback recycles cash into the next cohort sooner, which can beat a lower acquisition cost outright.; SeeCustomer acquisition cost,Contribution margin
Return on ad spendROAS: Return on ad spend is revenue attributed to advertising divided by the cost of that advertising, usually as reported by the advertising platform itself.; Useful for comparing two campaigns inside one platform on one day. Close to meaningless as a business target, because the platform chose the base it is measured on.; SeeMarketing efficiency ratio,Attribution

Measurement & attribution

Attribution: Attribution is the assignment of credit for a conversion to one or more marketing touchpoints that preceded it.; Every attribution model is an assumption about causation, not a measurement of it. Two defensible models can disagree by a wide margin on the same data.; SeeLast-click attribution,Incrementality,Multi-touch attribution
Attribution window: An attribution window is the period after an ad interaction during which a conversion will still be credited to that interaction.; Two platforms with different windows will report different conversion counts from identical activity. Comparing them without normalising the window is meaningless.; SeeAttribution,Last-click attribution
Consent mode: Consent mode is a mechanism by which tags adjust their behaviour according to the consent choices a visitor has made, sending limited or no identifiers when consent is withheld.; Where consent is declined, platforms typically fall back to modelling. The resulting numbers are estimates, and treating them as observed is a common reporting error.; SeeModelled conversions,Server-side tracking
Holdout test: A holdout test measures incrementality by deliberately withholding advertising from a randomly selected or matched group and comparing outcomes against the exposed group.; It costs real revenue for the duration of the test. That cost is usually smaller than a year of scaling a channel that was taking credit rather than creating demand.; SeeIncrementality,Matched market test
Incrementality: Incrementality is the share of conversions that happened because of a marketing activity and would not have happened without it.; It is the only question attribution is really trying to answer, and the only one a controlled holdout test answers directly.; SeeHoldout test,Attribution
Last-click attribution: Last-click attribution assigns all credit for a conversion to the final marketing touchpoint before it.; It systematically favours channels that appear late in the journey — brand search, retargeting, coupon affiliates — over the ones that created the demand.; SeeAttribution,Incrementality
Marketing mix modellingMMM: Marketing mix modelling uses statistical regression on aggregate historical data to estimate how each marketing input contributed to sales.; It needs no user-level tracking, which is why it returned to favour under privacy restrictions. It also needs a long history and genuine variation in spend to say anything reliable.; SeeAttribution,Incrementality
Matched market test: A matched market test compares outcomes between regions with similar historical performance, where advertising is changed in one set and held constant in the other.; Useful where individual-level holdouts are impossible. Its validity depends entirely on how well the markets were matched before the test began.; SeeHoldout test,Incrementality
Minimum detectable effectMDE: Minimum detectable effect is the smallest difference between variants that a test is capable of detecting reliably, given its sample size.; Deciding it before the test starts prevents the most common failure in experimentation: running a test that never had the traffic to answer the question.; SeeA/B test,Statistical significance
Modelled conversions: Modelled conversions are conversions estimated statistically by an advertising platform when the actual event could not be observed, typically because of consent or tracking restrictions.; They are estimates presented alongside observed conversions, usually without visible distinction. Reporting that does not separate them overstates certainty.; SeeConsent mode,Server-side tracking
Multi-touch attributionMTA: Multi-touch attribution distributes credit for a conversion across several touchpoints according to a chosen rule or model.; Its accuracy depends on observing the full journey, which privacy restrictions and cross-device behaviour increasingly prevent.; SeeAttribution,Marketing mix modelling
Server-side tracking: Server-side tracking sends conversion data to advertising platforms from a server the advertiser controls, rather than from the visitor's browser.; It improves data completeness where browser restrictions block client-side collection. It does not remove the need for consent — it changes the transport, not the legal basis.; SeeModelled conversions,Consent mode
Statistical significance: Statistical significance is the degree of confidence that an observed difference between variants reflects a real effect rather than random variation.; Significance says nothing about size. A statistically significant improvement can be too small to matter commercially, and frequently is.; SeeA/B test,Minimum detectable effect

Channels & buying

Accepted leadSales accepted lead, SAL: An accepted lead is an enquiry that the sales team has reviewed and agreed is worth pursuing.; The correct optimisation target for lead generation. Optimising raw lead volume instead reliably produces enquiries nobody works.; SeeCost per lead,Lead scoring
Affiliate marketing: Affiliate marketing pays third-party partners a commission for driving a defined action, usually a sale or a qualified lead.; Its central risk is paying full commission for customers who were already buying. Differentiated commission rates are the structural fix.; SeeLast-click attribution,Incrementality
Frequency capping: Frequency capping limits how many times a single person may be shown a particular advertisement within a defined period.; Uncapped retargeting reaches the point of irritation faster than most reporting reveals, because the same reporting counts the annoying impressions as reach.; SeeRetargeting,Programmatic advertising
Lead scoring: Lead scoring assigns a numerical value to an enquiry based on attributes and behaviour, to estimate how likely it is to convert.; It is only as good as the outcome data behind it. A score never validated against closed revenue is an opinion with a number attached.; SeeAccepted lead,Cost per lead
Native advertising: Native advertising is paid placement designed to match the form and feel of the surrounding editorial content.; Performance networks such as PropellerAds and RollerAds operate largely in this space, reaching inventory the major platforms do not, at different prices and different quality variance.; SeeProgrammatic advertising,Paid media
Paid media: Paid media is advertising space bought from a platform or publisher, as distinct from owned channels a brand controls or earned coverage it does not pay for.; It is one input into performance marketing rather than a synonym for it.; SeePerformance marketing,Programmatic advertising
Performance marketing: Performance marketing is marketing managed against measurable business outcomes such as acquisition cost or payback period, rather than against reach or awareness.; The defining feature is the target, not the channel. Any channel can be run this way if its contribution can be measured credibly.; SeePaid media,Customer acquisition cost
Programmatic advertising: Programmatic advertising is the automated buying and selling of ad inventory through real-time auctions rather than direct negotiation with publishers.; It buys reach efficiently and makes inventory quality hard to see. Placement transparency is worth insisting on.; SeeNative advertising,Frequency capping
RetargetingRemarketing: Retargeting serves advertising to people who have already interacted with a brand, typically by visiting its website.; The channel most prone to overstating its contribution, because its audience is by definition already interested. A holdout test is the honest way to size it.; SeeIncrementality,Frequency capping

Creative & conversion

A/B testSplit test: An A/B test randomly divides traffic between two or more variants and compares their performance against a single chosen metric.; Valid only when assignment is genuinely random and the sample is large enough for the effect being sought. Most inconclusive tests were underpowered from the start.; SeeStatistical significance,Minimum detectable effect
Conversion rate optimisationCRO: Conversion rate optimisation is the systematic improvement of the proportion of visitors who complete a desired action.; A conversion rate improvement that lowers lead quality is not an improvement. The metric has to be tied to something downstream to mean anything.; SeeA/B test,Landing page
Creative fatigue: Creative fatigue is the decline in an advertisement's performance as the target audience sees it repeatedly.; Often confused with audience saturation. The distinction matters: new creative fixes fatigue, while a larger audience is the only fix for saturation.; SeeFrequency capping,Creative testing
Creative testing: Creative testing compares advertising variants under controlled conditions to establish which performs better against a defined outcome.; Testing many variants of the same idea measures execution. Testing genuinely different ideas measures strategy, and usually returns more.; SeeA/B test,Creative fatigue
Friction: Friction is anything in a conversion path that increases the effort required to complete it, such as additional form fields or verification steps.; Not uniformly bad. Friction placed after the value is understood filters mostly in the right direction; friction placed before it repels everyone equally.; SeeConversion rate optimisation,Accepted lead
Landing page: A landing page is the page a visitor arrives at after clicking an advertisement, built for one specific audience and one specific action.; Frequently the largest single lever on acquisition cost, and the one most often treated as a downstream detail of the media buy.; SeeConversion rate optimisation,Message match
Message match: Message match is the degree of consistency between the promise made in an advertisement and the content of the page it leads to.; A mismatch shows up as a high bounce rate that looks like a traffic quality problem and is actually a page problem.; SeeLanding page,Conversion rate optimisation

Lifecycle & retention

Churn rate: Churn rate is the proportion of customers who stop being active over a defined period.; The inverse of retention, and the more intuitive framing for subscription businesses. Both hide the same thing: churn is rarely uniform across cohorts.; SeeRetention rate,Cohort analysis
Reactivation: Reactivation is marketing directed at lapsed customers with the aim of restoring them to active status.; Usually far cheaper than new acquisition, and usually undercounted, because the revenue often lands in whichever channel touched them last.; SeeChurn rate,Attribution
Repeat purchase rate: Repeat purchase rate is the proportion of customers who buy more than once within a defined period.; In transactional businesses it is the single most powerful lever on acquisition budget, and almost always cheaper to move than media efficiency.; SeeRetention rate,Lifetime value
Retention rate: Retention rate is the proportion of customers who remain active over a defined period.; It sets the ceiling on lifetime value, and therefore on what can be paid to acquire a customer. Improving it raises the acquisition ceiling for every channel simultaneously.; SeeChurn rate,Lifetime value
RFM segmentation: RFM segmentation groups customers by how recently they purchased, how frequently they purchase, and how much they spend.; Crude, decades old, and still outperforms most elaborate segmentation schemes for deciding who to contact next.; SeeCohort analysis,Reactivation

Search & AI search

Answer engine: An answer engine is a system that responds to a query with a synthesised answer rather than a list of links, typically citing sources within the response.; Its economics differ from classic search: a citation can deliver influence without a click, which breaks reporting built entirely on sessions.; SeeGenerative engine optimisation,Zero-click search
E-E-A-T: E-E-A-T stands for experience, expertise, authoritativeness and trustworthiness — the qualities Google's published rater guidelines use to assess content quality.; Not a direct ranking factor but a description of what the ranking systems try to approximate. Identified authors with real credentials are the most actionable part of it.; SeeEntity,Search engine optimisation
Entity: An entity is a distinct thing — a company, a person, a product — that a search or answer system recognises and holds information about, independently of any single web page.; Consistent naming, descriptions and profile links across the web are what let a system resolve scattered mentions into one entity rather than several vague ones.; SeeStructured data,E-E-A-T
Generative engine optimisationGEO: Generative engine optimisation is the practice of structuring content so that AI answer engines cite or quote it when generating answers.; It overlaps with SEO but optimises for being the source inside an answer rather than a link beside it, which rewards direct answers, self-contained definitions, cited figures and tables.; SeeAnswer engine,Search engine optimisation
Pillar page: A pillar page is a comprehensive page covering a broad subject at a high level, linking out to more detailed pages on its component topics.; It earns links and citations on the strength of completeness, then passes that authority to the specific pages that convert.; SeeTopic cluster,Search engine optimisation
Search engine optimisationSEO: Search engine optimisation is the practice of improving a site's visibility in the unpaid results of search engines.; Now has two distinct targets: ranking in classic results, and being citable by answer engines. The techniques overlap heavily but not completely.; SeeGenerative engine optimisation,Structured data
Structured dataSchema markup: Structured data is machine-readable markup that describes what a page's content means, using a shared vocabulary such as schema.org.; It removes ambiguity about what a page is and who wrote it — which matters more to systems deciding what to cite than to systems deciding what to rank.; SeeSearch engine optimisation,Entity
Topic cluster: A topic cluster is a group of related pages covering one subject in depth, organised around a central hub page that links to and from each supporting page.; The structure signals depth on a subject rather than isolated coverage, and it prevents several of your own pages from competing for the same query.; SeeSearch engine optimisation,Pillar page
Zero-click search: A zero-click search is a query resolved on the results page itself, without the user visiting any result.; AI-generated summaries extend this to far more complex queries than the featured snippets that preceded them, which changes what organic visibility is worth measuring.; SeeAnswer engine,Search engine optimisation

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