UTM parameters explained, with the rules that stop them rotting

A UTM parameter is a query string tag that travels with a click and tells the analytics tool on the other end where the click came from. Five of them exist, they are plain text, and nothing validates them. That last part is why most campaign reports are a mess: Instagram, instagram, IG and insta are four sources as far as any analytics tool is concerned.

What each tag is for

Parameter	Answers	Good values
utm_source	Which specific place	instagram, newsletter, partner_blog
utm_medium	Which kind of channel	social, email, cpc, qr, print, sms
utm_campaign	Which push	diwali_2026, launch_v3
utm_content	Which link, when two share the rest	header_button, footer_link
utm_term	Which paid keyword	usually empty

Source and medium are the pair that carry the weight. Medium should be a short closed list you decide once and never extend casually — the moment you have both social and social-media, every report needs a mental find-and-replace. Source is the specific origin inside that medium.

Campaign is the thing you would name in a meeting. Content is the tiebreaker, and it is the tag people skip and then regret: two links to the same page in the same email, untagged, are one row in the report forever.

The ones nobody mentions

Google Analytics 4 also recognises a handful of newer parameters beyond the classic five: utm_id for a campaign identifier that survives a renamed campaign, plus utm_source_platform, utm_creative_format and utm_marketing_tactic for the ad-platform metadata that used to be crammed into utm_content.

Most people should ignore all four. The exception is utm_id: if you run the same campaign across several tools and each of them names it slightly differently, a stable id is the only thing that lets you stitch the rows back together later. Set it once, keep it forever, and let the human-readable campaign name change as often as marketing wants it to.

The rules that keep them useful

1. 1

   Lower case everything, always

   Not a style preference. GA4 reports Email and email as separate sources and there is no way to merge them afterwards without reprocessing.

2. 2

   Underscores, not spaces

   A space becomes %20 in the URL and an ugly value in the report. Pick underscore or hyphen and never mix them.

3. 3

   Write the medium list down

   Six or seven values, kept in the same document as the campaign brief. Everyone tagging links reads from it.

4. 4

   Never tag internal links

   A UTM tag on a link inside your own site overwrites the original campaign attribution for that session. The visitor arrived from Instagram; one tagged internal link and the report says they arrived from your own footer.

Attaching them to a short link instead

Tagged URLs are long and ugly, which is a real problem in an SMS, a bio or anything printed. On gc.mw the parameters can live on the link rather than in the URL you share.

In the link editor, the UTM parameters section takes the five values. On every redirect they are appended to the destination, so gc.mw/menu arrives at the destination as a fully tagged URL while the thing you printed stays ten characters long. Change utm_campaign next month and every existing copy of the link starts reporting under the new name — including the one on the poster.

One rule governs collisions: a parameter already present on the destination URL wins. If the destination is https://example.com/sale?utm_source=partner, the link's own utm_source is not applied. That protects attribution somebody else set up deliberately, and it means you should keep the destination URL clean if you want the link's tags to do the work.

Reading them back

In the gc.mw dashboard, tagged clicks appear under UTM campaigns on the analytics page from the Pro tier upwards. That view answers a different question from the one your website analytics answers: it counts people who asked for the link, including everyone who never finished loading the destination. Compare the two and the gap is your landing page's real drop-off.

For anything printed, use utm_medium=print and a utm_source that names the physical place — shop_window, table_tent, flyer_batch2. Combine that with a separate short link per placement and you get something most print campaigns never produce: a per-placement number you can defend.