Glossary
Core concepts explained in simple terms in the context of practice.
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CAPI Gateway: the middle layer between your events and the platform
A CAPI gateway is a self-hosted middle layer that receives events from your pixel and server, applies deduplication, and forwards them to the ad platform's Conversions API. Meta and TikTok ship first-party gateways.
Click ID: the ad click parameter platforms use to attribute events
A click ID is the parameter an ad platform appends to your landing page URL on every click - fbclid on Meta, ttclid on TikTok, rdt_cid on Reddit, ScCid on Snapchat. Captured and forwarded, it is the strongest match key a server event can carry.
Conversion ID: one identifier for one conversion, on every platform
A conversion ID is the identifier your systems attach to one distinct conversion on every channel reporting it - event_id on Meta and TikTok, conversion_id on Reddit, client_dedup_id on Snapchat - so deduplication keeps one copy instead of two.
Conversions API (CAPI): Meta's server-side conversion interface
The Conversions API is Meta's interface for sending web, app and offline conversion events directly from your server, complementing the browser pixel.
Custom conversion: measuring a business action Meta's standard events do not cover
A custom conversion is a Meta rule that counts events matching conditions you define - URL, event name or parameter - when no standard event fits the goal.
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Enhanced Match: hashed first-party identifiers sent with browser events
Enhanced Match - TikTok's name; Meta calls it Advanced Matching - sends hashed first-party identifiers such as email and phone alongside browser pixel events, so more events match to real user profiles.
Event Quality Score: how platforms grade the completeness of your events
An event quality score is the platform's grade of how complete an event payload is: Meta's Event Match Quality runs 0-10, Pinterest targets a "Good" EQS, Reddit and Snapchat surface warnings in their test views.
Events API: TikTok's server-side interface for conversion events
The Events API is TikTok's interface for sending conversion events from your server, complementing the TikTok Pixel where browser tracking is lost.
event_id and deduplication: stop double-counting conversions
Double-counted conversions wreck your pixel's optimisation. Learn how the event_id is built from sub_id, event name and UTC time, and the three layers that keep Most from sending the same conversion twice.
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Match key: the identifiers that tie a server event to a real user
A match key is an identifier in an event payload - click ID, hashed email or phone, IP with user agent, mobile ad ID - that lets the ad platform tie the event to a real profile. Snapchat rejects events without one.
Match rate: how many of your events a platform can tie to a real user
Match rate is the share of sent events that TikTok (or Meta) successfully matched to a real user profile - the quality metric of server-side delivery.
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Server-side tracking: delivering conversions from your infrastructure
Server-side tracking sends conversion events from your server (or tracker) directly to ad platforms, instead of relying on browser tags and cookies.
Standard events: Meta's fixed vocabulary for conversion actions
Standard events are Meta's predefined event names - Purchase, Lead, InitiateCheckout and others - that its optimisation and reporting understand out of the box.