UTM Parameters

UTM parameters are tags appended to a URL that tell GA4 which campaign, source, and medium a click came from.

You add them to the end of a link as query parameters, and when someone clicks through, GA4 reads them and records where the visit came from. The core three are utm_source, utm_medium, and utm_campaign, and they feed directly into channel grouping and attribution. Without them, most of your paid and email traffic lands in Direct or gets mislabeled.

A newsletter link tagged with utm_source of newsletter, utm_medium of email, and utm_campaign of spring-launch shows up in GA4 attributed to that exact campaign. Send the same link untagged and GA4 has nothing to read, so the clicks scatter into Direct and the campaign looks like it drove nothing.

UTMs are case-sensitive and completely manual, which makes them fragile. Email and Email are two different sources to GA4, and one person using cpc while another uses ppc splinters the same campaign across rows. Agree on a naming convention, write it down, and use a builder, because inconsistent tags are the most common reason channel reports are a mess.

Tag it right or it never happened.