UTM parameters
Measurement and data
Measurement and data
UTM parameters are snippets you add to a link so your analytics shows which source, medium and campaign a visitor came from.
A link with ?utm_source=newsletter&utm_medium=email&utm_campaign=summer shows exactly where traffic came from in GA4, even when the referring source doesn't pass that itself.
Agree one convention (all lowercase, fixed source names) and write it down. Two spellings of the same channel split your reporting without anyone noticing.
In practice
Never use UTMs on internal links within your own site: it starts a new session and wipes the original source.