UTM Parameters Explained: Source, Medium, and Campaign

UTM parameters are small tags appended to a URL that tell Google Analytics (or any analytics platform that reads them) where a visit came from. They don't change what the page shows — they're purely a tracking label attached to the link.

The three that matter most

Source identifies the specific origin of the traffic — a platform or publication, like "newsletter" or "instagram." Medium is the general category that source belongs to, like "email" or "social." Campaign identifies the specific push the link belongs to, like "spring-launch" or "black-friday-2026." Together, they let you filter traffic by exactly which link drove a visit, not just which site.

The naming mistake that breaks reports silently

Analytics platforms treat UTM values as case-sensitive and exact-match — "Newsletter," "newsletter," and "news-letter" will all show up as three separate sources in your reports, splitting what should be one clean data set into fragments. The fix is entirely about discipline: pick a naming convention (lowercase, hyphenated is the common standard) and use it identically every time, ideally from a shared reference sheet if more than one person creates links.

When not to bother with UTMs

Internal links between pages on your own site don't need UTM tags — analytics tools already track internal navigation natively, and adding UTM parameters to internal links can actually corrupt session data by making the platform think a new session started. UTMs are for links that live somewhere outside your own site: social posts, emails, ads, and other external placements.