What is UTM Parameters?
Tags appended to a URL that tell analytics where a visitor came from.
?utm_source=newsletter&utm_medium=email&utm_campaign=diwali-2026
A worked example
Two links in the same WhatsApp broadcast go untagged. Both arrive in analytics as direct traffic, indistinguishable from someone typing your address. The campaign appears to have produced nothing, and the next budget conversation reflects that.
Why it matters
UTM parameters are how you attribute traffic that platforms cannot identify for you: email, WhatsApp, QR codes on packaging, offline print, partner links, influencer bios. Without them that traffic lands in direct or referral and the channel looks like it did nothing.
The failure is usually inconsistency rather than absence. Analytics treats values as case-sensitive strings, so Facebook, facebook and FaceBook become three separate sources, and a report that should show one channel shows three fragments of it. Agreeing a lowercase convention and documenting it takes an hour and prevents months of confusion.
For anyone measuring offline or messaging-led activity, this is the difference between a channel that reports results and one that appears to be free.
The nuance most people miss
Never put UTM parameters on internal links between pages of your own site. Doing so starts a new session and overwrites the original acquisition source, so a customer who arrived from a Google ad and then clicked a tagged internal banner gets recorded as coming from that banner. Your paid campaign loses the conversion it earned. Use event tracking for internal clicks and keep UTMs for traffic arriving from outside.
Common mistakes
- Tagging internal links, which overwrites the real acquisition source
- Inconsistent capitalisation, splitting one channel into several in reporting
- Leaving out utm_medium, which is what channel grouping relies on
- Putting personal or sensitive data in a parameter, where it becomes visible in reports and shared URLs