Glossary
UTM parameters
Tags added to a URL that record which source, medium, and campaign sent a visitor to a site.
Also called: UTM tags, campaign tracking parameters
UTM parameters are short key-value pairs appended to the end of a URL to label where a click came from. The five standard fields are utm_source, utm_medium, utm_campaign, utm_term, and utm_content, originally introduced by Google's Urchin analytics product and now supported as a convention across nearly every analytics platform.
When a visitor lands on a page through a tagged link, the analytics tool reads the parameters and stores them as traffic-source dimensions on that session, overriding or supplementing whatever referrer data the browser sends. This lets marketers manually label traffic from channels that would otherwise be lumped together, such as distinguishing an Instagram bio link from a paid Instagram ad.
UTMs are the backbone of manual attribution modeling for campaigns that platforms don't tag automatically, such as email, social bios, and print QR codes. The main pitfalls are inconsistent naming (utm_source=fb vs facebook vs Facebook fragments reports), UTMs persisting if a link is bookmarked or forwarded and so misattributing a later, unrelated visit, and some email clients or link shorteners stripping or mangling the parameters before the click completes.
Last reviewed September 19, 2026