Attribution
UTM content
Also called utm_content.
UTM content is the parameter that tells links or creatives apart inside one campaign. It is written utm_content.
How it is measured
The value is read from the landing address and attached to the session. Use it for the version of an ad, the position of a link, or the variant of an email button.
Pair it with the campaign and compare click-through or conversion by content value. Keep the list of values short, or each row will have too few sessions.
Worked example
A bookshop sends a newsletter with two links to the same new-release page: one in the header image and one in the text. They are tagged 'hero-image' and 'text-link'. The links get 310 and 520 sessions.
The text link also gets 41 orders against 12 for the image. The shop moves the call to action into text and keeps the image as decoration in the next issue.
How it differs
A UTM content tag separates versions within a campaign. A UTM campaign tag names the campaign. Content is the smaller unit that sits inside the campaign.
Common errors
Leaving it blank on emails with several links. Using generic values like 'link1'. Using too many values. Putting the campaign name in the field. Forgetting to record which value was which.
In practice
Tag each link in a multi-link email with a clear position or version. Compare conversions per link after a send. Use what you learn to place the next one.