The source/medium reports are the granular view of where your traffic is coming from. This would be one of the main reports for a marketer, especially in terms of gauging not only how much traffic you’re getting from each place but how engaged it is, how well it converts, what’s the average revenue per user etc.

It’s only by comparing the different channels that you can get a decent picture of what’s happening. For example, your overall website’s conversion rate is just an average, and in practice it will differ a lot between different source/medium combinations.

You should also make sure you’re clear on the difference between these 3 columns in GA4, if not see this earlier post in the sequence:

• Source/medium
• Session source/medium
• First user source/medium

Medium

Medium contains information about how the user got to your website. Here are some default values and what they mean:

• organic: GA4 reserves this for known search engines like Google, Microsoft, DuckDuckGo, Ecosia etc. This is your SEO traffic.
• cpc: If you link your Google Ads account, this is how GA4 will label your traffic.
• referral: This is the default value for when a website links to yours and someone clicks on the link, unless it’s set to the one above.
• (not set): This means the session never got a medium. If you get a lot of those, it might mean there are tracking code issues.
• (none): This means the traffic was direct or the data is missing. This can mean a range of different things:
  • Someone typed the page into their URL bar directly
  • Someone followed a bookmark
  • Someone clicked on a link where the website/app chooses not to pass referral data onto the website it’s sending traffic to
  • Someone clicked on a link that opened up a new browser session (eg. from an email/QR code etc) and it wasn’t UTM tagged.

Generally you’d want to reduce your direct (none) traffic and the above is not going to be enough for most websites. For the rest, it’s up to you to add values to links people click. This is called UTM tagging and here’s a basic guide. Below are some values you might want to consider:

• paid-social for social ads
• social or organic-social for any organic social posts you tag
• email for links in your EDMs
• qr for links in QR codes
• redirect if you’ve redirected a vanity domain to a deep link
• print if you have a brochure that sends people to a vanity link
• sms for links in SMSes
• etc

Source

The source is where people are actually coming from. The main default values are:

• (direct): This is for direct traffic, see the notes above on (none)
• google, bing, duckduckgo etc: For organic traffic, GA4 will display the search engine name regardless of what actual domain people are coming from
• subdomain.somewebsite.com: Otherwise the default is just what domain people are coming from. GA4 keeps the subdomain (except www which it removes). There are 2 considerations for this:
  • Sometimes a website might use another domain to redirect traffic in which case you’ll see the domain just before the user hits your website. For example, Twitter (x.com) sends traffic through t.co so that’s what shows up in your reports.
  • Some websites might send traffic through multiple subdomains. For example, Facebook might show as facebook.com, m.facebook.com, lm.facebook.com, l.facebook.com etc. These will be separate rows in your report but there’s no real distinction. If you’re using Looker Studio you might want to collate them into one row otherwise you can use channel groupings (see the next post in this series).

If you are using custom UTM tags, you can make this anything you want, some examples might be:

• customers for EDMs or offline
• specific-list-name for EDMs
• edm-platform-name for EDMs
• ad-network-name for custom digital ad purchasing

Many platforms will prefill this for you automatically, which you should look into for your main marketing platforms. For example, in Meta Ads if you set the source to be {{site_source_name}} it will show fb for clicks from Facebook, ig for Instagram, an for Audience Network etc.