Glossary

One page per term, defined the way the industry actually uses it — including the ones two teams use to mean opposite things.

Assisted conversion A touchpoint that appeared somewhere in the journey without being the last one. It records presence, not contribution — the two get read as the same thing constantly.
Attribution model The rule that decides how credit for a conversion is divided among the touchpoints before it. Every model is a choice about what to reward, not a discovery about what happened.
Attribution window The period after an ad interaction during which a later conversion is still credited to that interaction. Once it closes, the conversion is counted as coming from somewhere else.
Click ID A unique identifier an ad platform appends to the landing page URL when someone clicks an ad, so a later conversion can be tied back to that exact click.
Consent mode A mechanism that tells tags whether a visitor consented, so they adjust behaviour instead of firing or not firing. Consent is the permission; consent mode is the plumbing.
Conversion An outcome you decided to count. The definition is yours, which is why two teams reporting "conversions" are often counting different things and comparing regardless.
Conversion rate Conversions divided by something. The numerator is usually agreed and the denominator rarely is, which is why the same performance produces different rates in different tools.
Cookie window How long a tracking cookie stays valid after it is set. Often confused with the attribution window, which is a reporting rule rather than a storage limit.
Customer lifetime value What a customer is worth across the whole relationship rather than one purchase. Usually a prediction, often reported as though it were a measurement.
Data clean room A controlled environment where two parties analyse their combined data without either seeing the other's raw records. Aggregate answers come out; row-level data does not.
Deduplication Recognising that two records describe the same event, so one purchase reported twice is counted once. The routine failure mode of sending events from the browser and the server.
First-party data Information you collected directly from your own customers through your own properties. Distinct from data bought or obtained through an intermediary.
Hashing Converting a value into a fixed-length string that cannot be reversed, so two systems can check whether they hold the same value without either sending the value itself.
Holdout test Deliberately withholding advertising from a comparable group so the difference in outcomes shows what the advertising actually caused. The method behind an incrementality claim.
Identity resolution Deciding that separate records — a click, a session, an order, an email — belong to the same person. Everything downstream inherits whatever this gets wrong.
Impression An ad being served. Not an ad being viewable, and not an ad being seen — three different things routinely reported under one word.
Incrementality Whether a marketing activity actually caused conversions that would not have happened without it. The question attribution reports cannot answer.
Last-click attribution Giving a conversion entirely to the final click before it. Still the most common model, and the one that most reliably misprices everything upstream.
Marketing mix modelling A statistical model that estimates each channel's contribution from aggregate spend and outcome data over time, without tracking individuals. Often called MMM.
Match rate The share of records you sent that a platform could tie to a known person. The single number that tells you whether an identity setup is working, and the first one to check when results look thin.
Modeled conversions Conversions an ad platform estimates statistically rather than observes directly, used to fill gaps where consent, tracking prevention or privacy limits block measurement.
PII Personally identifiable information — data that identifies a specific person. The category is narrower than most regulation, which is why "we removed the PII" is rarely the whole answer.
Server-side tagging Sending marketing and analytics events from your own server instead of from the visitor's browser, so a request the browser might block is made somewhere it cannot be.
Session A group of one visitor's activity treated as a single visit. The grouping is a rule each tool applies, not an event, which is why two tools rarely agree on the count.
Signal loss The industry term for measurement data that no longer arrives — through consent refusal, browser restrictions and platform limits. It describes a change in visibility, not a change in behaviour.
Statistical significance A statement about how likely a difference this large would be if there were no real effect. It is not a measure of how large, how important, or how certain the effect is.
Tracking prevention Browser features that limit how long identifiers survive and which requests are allowed, applied by default to everyone. Separate from consent, and not something the visitor opted into.
UTM parameters Tags you add to a URL to describe where a visit came from. They label the traffic for your own analytics; they do not identify the click to the ad platform.
View-through conversion A conversion credited to an ad the person saw but never clicked. The weakest common attribution signal, and the one most likely to inflate a channel.
Zero-party data Information a customer deliberately gave you about themselves — preferences, intent, stated needs — rather than something you observed. A marketing coinage, not a legal category.