UTM parameters

UTM stands for Urchin Tracking Module – the name comes from Urchin, the analytics system Google bought in 2005 and built Google Analytics on. The parameters are added to the end of a URL after a question mark: ?utm_source=newsletter&utm_medium=email&utm_campaign=august. The analytics tool on the landing page reads the fields and groups the visit by source, channel and campaign.

The 5 fields have fixed roles: utm_source is the specific source (a site name, a newsletter), utm_medium is the channel type (email, social, affiliate), utm_campaign is the campaign name, utm_term is used for keywords in paid search, and utm_content distinguishes variants – for example 2 banners in the same campaign. Source, medium and campaign carry most of the load in practice; term and content are detail fields. GA4 also knows newer fields such as utm_source_platform and utm_creative_format, but the 5 classic ones cover the vast majority of needs.

In affiliate marketing, UTM parameters live alongside the tracking itself. Attribution is decided by the network's click ID – not by UTM fields. The parameters serve 2 other purposes: the store can see affiliate traffic as a channel in its analytics tool, and the affiliate can label their links to see which placements drive clicks. If the parameters are lost along the way, only the statistics disappear – the commission follows the click ID. Stores that want to separate affiliate traffic in their analytics tool often ask affiliates to use utm_medium=affiliate with an agreed source name.