A link with UTM parameters looks like this: ?utm_source=newsletter&utm_medium=email&utm_campaign=spring. The page looks the same, but GA4 knows the visit came from the spring newsletter.
Where to use them
Anywhere analytics cannot recognise the source on its own: newsletters, social posts, QR codes on flyers, links in PDFs. Google Ads does not need them when linked to GA4.
The one rule
Name them consistently. “Newsletter”, “newsletter” and “NL” are three different sources to analytics. Keep one sheet with the agreed names.
