Glossary
Conversion tracking, term by term
This glossary defines the terms that come up when you work on conversion tracking and attribution: signal loss, the Conversions API, click IDs, Event Match Quality and the rest. Every entry opens with a direct, factual definition, then explains how the concept affects your ad performance.
Signal loss
Signal loss is the gap between the conversions that actually happen and the conversions your ad platforms can see and attribute. It is caused by ad blockers, browser privacy features such as Safari’s Intelligent Tracking Prevention, iOS App Tracking Transparency, short-lived cookies and missing consent. All of these stop browser-based tracking from reporting events.
Read the definition→Conversions API
The Conversions API (CAPI) is Meta’s interface for sending conversion events to Meta directly from a server, instead of from the visitor’s browser through the Meta pixel. Server events can carry hashed customer identifiers, click IDs and order details, and are designed to run alongside the pixel with deduplication.
Read the definition→Event deduplication
Event deduplication is the process by which an ad platform recognizes that two reports (typically one from the browser pixel and one from a server) describe the same conversion, and counts it only once. On Meta, the browser and server copies are paired primarily by event name plus a shared event_id.
Read the definition→event_id
An event_id is a unique identifier attached to a conversion event so ad platforms can deduplicate multiple reports of the same conversion, most commonly a browser pixel event and a server-side event. When both copies carry the same event_id and event name, the platform keeps exactly one.
Read the definition→Event Match Quality (EMQ)
Event Match Quality (EMQ) is a score from 0 to 10 that Meta shows in Events Manager for each event type received through the Conversions API. It estimates how effective the customer information attached to your server events is likely to be at matching those events to Meta accounts.
Read the definition→fbclid, _fbc and _fbp
fbclid is the click identifier Meta appends to your landing-page URL when someone clicks a Meta ad. _fbc and _fbp are first-party cookies set by the Meta pixel: _fbc stores that click ID and _fbp identifies the browser. Both can be sent as the fbc and fbp parameters in Conversions API events to improve matching and attribution.
Read the definition→gclid
The gclid (Google Click Identifier) is a URL parameter that Google Ads appends to your landing-page URL when auto-tagging is enabled. It uniquely identifies the ad click, so both Google and your own systems can tie later conversions back to the exact campaign, ad group and ad that produced the click.
Read the definition→ttclid
The ttclid is TikTok’s click identifier: a parameter TikTok appends to your landing-page URL when a user clicks a TikTok ad. Sending the ttclid with conversions reported through the TikTok Events API links those events back to the specific ad click, which improves attribution and match rates.
Read the definition→Server-side tracking
Server-side tracking sends conversion events to ad and analytics platforms from a server, rather than from JavaScript running in the visitor’s browser. Because delivery is server-to-server, events are unaffected by ad blockers, browser tracking prevention or a tab closed before the pixel fired.
Read the definition→First-party data
First-party data is information a business collects directly from its own audience on its own properties: website visits, orders, sign-ups, email addresses and app activity. It contrasts with third-party data, which is collected by another company across sites and apps it does not own.
Read the definition→Start sending signals your ad platforms can actually use.
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