UTM parameters
Tags added to the end of a link to know where each visit comes from: which campaign, which ad, which email.
Technical meaning
Five standard parameters (utm_source, utm_medium, utm_campaign, utm_content, utm_term), read by GA4 and captured by the form so they are stored in the CRM with the enquiry. A naming convention written once and applied everywhere is the condition for readable attribution. Contrast sets it before the first campaign.
See tracking and data reporting