What is a UTM?
A UTM is a small piece of text you add to the end of a link so your analytics can tell exactly where a click came from. It is how you know a visitor arrived from your newsletter rather than a Google search.
What the parameters mean
A UTM-tagged link carries labelled values. The three you will use most:
- utm_source: where it came from, e.g. newsletter, facebook.
- utm_medium: the type of traffic, e.g. email, cpc, social.
- utm_campaign: the specific campaign, e.g. spring-sale.
So ?utm_source=newsletter&utm_medium=email&utm_campaign=spring-sale tells GA4 to file that visit under your spring-sale email, not generic traffic.
When you need them, and when you don't
Use UTMs for links you control that analytics cannot otherwise identify: emails, social posts, partner links, QR codes. You do not need them on Google or Meta ads, which auto-tag themselves; adding UTMs there can actually override the richer automatic data.
The mistakes that wreck reports
Inconsistent casing (Email vs email creates two rows), tagging internal links (which resets the visitor's source mid-session), and forgetting a medium. Keep a simple naming convention and your channel reports stay clean. Inconsistent tagging is a common cause of paid traffic showing as organic.
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