First-click vs last-click referrer
A visitor often touches several sources before converting. First-click attribution credits the referrer that started the journey; last-click credits the one immediately before conversion. The same session can therefore be attributed to different referrers depending on the model — which is why the original inbound source is easy to lose without persisted campaign data. This page explains the distinction and the UTM approach.
What the two models credit
Most visitors arrive through more than one source over time: a social post introduces them, an email reminds them, and a direct visit closes the sale. The HTTP referrer only ever describes the most recent navigation, so by default analytics tends toward last-click — crediting whatever immediately preceded the conversion.
First-click attribution instead credits the source that started the journey. The same conversion can therefore be assigned to entirely different referrers depending on the model: the introducing social post under first-click, or the closing email under last-click. Neither is wrong; they answer different questions about how traffic is acquired versus converted.
- Last-click credits the source right before conversion
- First-click credits the source that began the journey
- The live referrer only ever reflects the latest navigation
Keeping the original source recoverable
Because the referrer is overwritten on every new navigation, first-click attribution is only possible if you capture the original source at the very first visit. Read the inbound referrer and UTM parameters on first load and persist them, so later touches do not erase the first.
Tag inbound links with utm_source, utm_medium, and utm_campaign so the first touch is unambiguous rather than a trimmed or missing referrer. With the original source stored, you can report both first- and last-click without depending on a referrer that no longer exists by the time someone converts.
How it appears in analytics and logs
If a conversion is credited to your own site, an email, or a payment step rather than the campaign that introduced the visitor, you are seeing last-click attribution discard the first touch. The original referrer is only recoverable if it was captured at the first visit.
Diagnostic use case
Decide whether to credit the source that introduced a visitor or the one that closed the conversion, and capture the original referrer so first-click attribution remains possible.
What WebmasterID can help detect
WebmasterID records the referrer and UTM parameters at first load, so the original source is preserved and available for first-click attribution even after later last-click touches overwrite the live referrer.
Common mistakes
- Assuming last-click is the only model because the live referrer shows the latest source.
- Not capturing the inbound source at first visit, making first-click attribution impossible later.
- Relying on the referrer for the first touch when trimming or app handoffs leave it missing.
Privacy and accuracy notes
Attribution models operate on coarse source labels, not visitor identity. WebmasterID treats first- and last-touch sources as channel signals and never builds cross-site identity profiles to stitch them together.
Related pages
- UTM vs referrer: which wins
When a visit carries both a referrer and UTM campaign parameters, most analytics treat the explicit UTM source as authoritative over the inferred referrer. That is usually correct: UTM tags describe intent you set deliberately, while a referrer is whatever the browser happened to send. Understanding the precedence prevents double-counting and mis-attribution.
- Campaign vs referrer precedence
A single visit can arrive with both a Referer header and UTM campaign parameters. Most analytics tools let the explicit campaign parameters take precedence over the inferred referrer, because a deliberate utm_source is a stronger signal than a host guess. Knowing the precedence order explains why a tagged link shows your campaign source even when the referrer differs.
- Cross-domain referrer loss
When a journey crosses between domains you own — a marketing site to an app subdomain, or a multi-domain checkout — the original source can be lost: the second domain sees the first as the referrer (a self-referral) and the inbound campaign is overwritten. This page explains cross-domain referrer loss and how exclusion lists plus persisted UTM parameters prevent it.
- Attribution analytics
Preserve the first-touch source alongside the last-click referrer.
Sources and verification notes
- MDN — Document.referrerThe referrer reflects only the most recent navigation, motivating first-touch capture.
- MDN — Referer header
Last reviewed 2026-06-24. Facts are checked against primary/official sources where available; uncertain specifics are marked “Data not yet verified” rather than guessed.