What UTMs are
UTM stands for Urchin Tracking Module — a convention introduced by an analytics company Google bought in 2005. Google Analytics, GA4, and most other analytics platforms still recognize them today. A UTM-tagged URL looks like https://example.com/?utm_source=newsletter&utm_medium=email&utm_campaign=spring-sale. The destination doesn't change — only the analytics view does.
The five UTM parameters
utm_source — where the traffic comes from (newsletter, google, facebook). utm_medium — the channel type (email, cpc, social, referral). utm_campaign — the campaign name (spring-sale, product-launch). utm_term — the keyword bid on (paid search only). utm_content — used to differentiate creatives or links within the same campaign (hero-cta vs footer-cta).
Naming conventions and gotchas
Use lowercase, hyphens, and consistent values. utm_source=Newsletter and utm_source=newsletter become two separate rows in analytics. Never tag internal links between pages of your own site — that overwrites the original attribution and inflates self-referrals.
Building UTM URLs quickly
Doing this by hand is error-prone. The Link Tools UTM Builder generates the URL for you and lets you copy it with one click.