Campaign dimension
The campaign dimension labels a visit with the marketing campaign that drove it. It is populated from the utm_campaign parameter on a tagged link, or auto-tagged by an ad platform's own click ID. Any visit without a campaign tag — most organic, direct, and untagged referral traffic — shows '(not set)', which is the absence of a campaign rather than a campaign named '(not set)'.
What this means
Campaign is the name you assign to a marketing effort, carried into analytics by the utm_campaign parameter on the click URL. Ad platforms that auto-tag (passing a click ID the analytics tool resolves) can also populate it without manual UTMs.
It is the dimension that lets you compare 'spring-sale' against 'newsletter-q2' — but only for traffic that actually carried a campaign tag.
Why '(not set)' dominates
Most traffic is not campaign-tagged: organic search, direct visits, and untagged referrals all arrive without utm_campaign, so they land in '(not set)'. That is expected. The warning sign is paid traffic showing '(not set)' — that means auto-tagging is off or UTMs are missing, and spend is going unattributed.
- Set by utm_campaign or ad-platform auto-tagging
- Untagged traffic => (not set), which is normal
- (not set) on paid traffic = broken tagging
How it appears in analytics and logs
A campaign value comes from utm_campaign or ad-platform auto-tagging. Heavy '(not set)' is normal for organic/direct traffic; heavy '(not set)' on paid traffic signals broken tagging.
Diagnostic use case
Use campaign to compare tagged marketing efforts, knowing it is only populated for tagged or auto-tagged traffic and that '(not set)' means no campaign was attached.
What WebmasterID can help detect
WebmasterID captures utm_campaign at ingest and keeps it tied to the originating click, so tagged campaigns stay attributable without third-party cookies.
Common mistakes
- Reading '(not set)' as a campaign named '(not set)'.
- Forgetting that organic/direct legitimately have no campaign.
- Missing that paid '(not set)' means tagging is broken.
Privacy and accuracy notes
Campaign is read from a URL parameter you set, not from the visitor's identity. WebmasterID records utm_campaign first-party and never infers campaigns from cross-site tracking.
Related pages
- Source / medium: the core traffic-origin dimension
Source/medium is the dimension that records where a visit came from (the source, e.g. google) and how it arrived (the medium, e.g. organic). It is derived from the referrer and UTM parameters, with rules that vary by tool. The big caveat: when neither is available, the visit lands in 'direct / (none)', which is a catch-all, not a channel.
- Default channel grouping
Default channel grouping is a derived dimension that maps each visit's source, medium, and campaign onto a fixed set of channels — Organic Search, Paid Search, Direct, Email, Referral, and more. GA4 applies an ordered set of rules at query time, so a visit only gets a channel if it matches the rule's source/medium pattern. Misclassification almost always traces back to untagged or mistagged campaigns.
- UTM parameters explained: the five tags and how to use them
UTM parameters are query-string tags you add to a link so analytics can attribute the visit to a campaign even when the referrer is missing. This page explains the five tags, a consistent naming convention, and the hard rule that UTM values are public — so they must never contain personal data or secrets.
- Campaign links
Build consistent, taggable campaign URLs.
Sources and verification notes
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.