What is utm_medium?

Who adds it

It's set by whoever tagged the link, or by the tool that tagged it. Microsoft Advertising sets it to cpc, Kit and Klaviyo set it to email, and Buffer sets it to social. Google's docs list cpc, banner and email as typical values.

What it means

It describes the type of traffic: paid search, email, social, affiliate and so on. Google Analytics 4 uses the medium, together with the source, to sort the visit into a default channel such as Email, Organic Social or Paid Search.

What to do with it

Use the values GA4's channel rules expect (email, social, cpc, referral, affiliate) if you want visits to land in the right channel. Values that match no rule end up as Unassigned in GA4.

How Vireo shows it

Vireo Pro's UTM campaigns card lists tagged visits by Source, Medium and Campaign, with visitors and pageviews. The tags are read from the first page of each visit, and the same tags feed revenue by source.

In the free plugin, Vireo drops the query string from page addresses, keeping only a few WordPress ones such as p and page_id, so a tagged URL counts as the same page as the untagged one. The visit is counted under the referrer it arrived with.

UTM campaigns are part of Vireo Pro. See UTM campaigns in the docs.

Sources

utm_medium : Marketing medium, for example: cpc, banner, email

URL builders: Collect campaign data with custom URLs - Analytics Help

Unassigned is the value Analytics uses when there are no other channel rules that match the event data.

Default channel group - Analytics Help