What Are UTM Parameters?

You sent a newsletter, ran an ad and posted on social. Traffic went up — but from which one? UTM parameters are how you answer that. They're small tags added to your links that tell analytics exactly where each visitor came from.

What a UTM actually is

A UTM parameter is just a query-string key on the end of a URL:

https://site.com/page?utm_source=newsletter&utm_medium=email&utm_campaign=spring_sale

When someone clicks, Google Analytics (and most other tools) reads those tags and attributes the visit to that source, channel and campaign. The page itself ignores them — they're purely for tracking.

The five parameters

• utm_source — the specific origin: google, newsletter, facebook. Answers who sent the traffic.
• utm_medium — the channel type: cpc, email, social, referral. Answers how.
• utm_campaign — the initiative: spring_sale, launch_2026. Answers which push.
• utm_term — the paid keyword, for search ads.
• utm_content — distinguishes two links in the same message, for A/B tests (e.g. logo_link vs text_link).

The first three are the essentials; the last two are optional.

Source vs medium — the confusing pair

People mix these up constantly. A simple rule: source is the brand name, medium is the category. Facebook is a source; social is its medium. Your newsletter is a source; email is the medium. If you can group several sources under one word, that word is your medium.

Consistency is everything

UTM values are case-sensitive. Email, email and e-mail become three separate rows in your reports, fragmenting your data. Pick conventions and stick to them:

• Always lowercase.
• Use underscores or hyphens for spaces — never actual spaces.
• Keep a shared spreadsheet of approved source/medium values.

Don't tag internal links

A classic mistake: adding UTMs to links between pages of your own site. This can overwrite the real acquisition source and break attribution. Only tag links that bring people to your site from outside.

Build clean links

Assembling these by hand invites typos. The UTM builder fills the fields, forces lowercase and URL-encodes the values so nothing breaks. To inspect an existing tagged link, drop it into the URL parser, and read the anatomy of a URL to see exactly where UTMs live.