Of the five UTM parameters, utm_medium is the one analytics platforms care about most. Google Analytics 4 uses it — more than source or campaign — to decide which default channel group a session belongs to. Get medium right and your Paid Search, Email and Organic Social rows make sense. Get it wrong and traffic slides into Unassigned, where insight goes to die.
What utm_medium means
utm_medium names the type of marketing channel a click arrived through. Not who sent it — that is utm_source — but how it traveled: paid search, email, organic social, display, referral, and so on. A single campaign usually spans several mediums: the same spring sale promoted by email (utm_medium=email), Instagram ads (utm_medium=paid-social) and a partner blog (utm_medium=referral).
The five parameters, in one sitting
| Parameter | Answers | Example |
|---|---|---|
utm_source | Who sent the traffic? | google, newsletter, partner-blog |
utm_medium | What channel type? | cpc, email, social |
utm_campaign | Which effort? | spring-launch |
utm_term | Which keyword? (paid search) | running-shoes |
utm_content | Which variant? | hero-banner-v2 |
Only the first three are needed for most tracking. Term and content are optional refinements for paid search and creative testing.
Why medium matters more than people think
Three reasons practitioners treat medium as the load-bearing parameter:
- Channel grouping. GA4's default channel rules key off medium values like
cpc,email,socialanddisplay. A nonstandard medium means manual rules or Unassigned traffic. - Budget questions. "How is paid performing versus organic?" is a medium question. If paid social is tagged
socialin one campaign andpaid-socialin another, the answer is fiction. - Comparability. Medium lets you compare the same campaign across channels — the spring launch via email versus via paid social — because campaign stays constant while medium varies.
A complete example URL
https://example.com/landing?utm_source=newsletter&utm_medium=email&utm_campaign=spring-launch
Read it aloud: the spring-launch campaign, sent by the newsletter, arriving through email. Each parameter earns its place. Draft your own controlled list with the free utm_medium generator before your next campaign goes out.