(none) : Traffic from a visitor typing your URL into a browser or going to a bookmark
gmb : Manually classified traffic from a Google business listing that has an Urchin Tracking Model (UTM) code . A UTM code is a piece of text added to the end of the URL of a link pointing to your website. It helps you track the performance of your digital marketing campaigns.
Referral : Traffic from other phone number in korea websites that are not search engines (including social networks)
cpc : Traffic from Google Ads
Source and medium.
Google Analytics may combine the traffic source and medium dimensions into another dimension called Session Source/Medium.
With this particular traffic source, Google Analytics shows that your Google traffic is coming from three different sources. And you can see that organic traffic accounts for the largest percentage.
Session Source / Media Table
While "google/organic" and "google/cpc" are automatically categorized, "google/gmb" traffic comes from a Google Business listing that has been tagged using UTM parameters.
You can also use UTM parameters to display traffic from specific marketing campaigns.
Bell
You can use the campaign dimension to associate your traffic with specific advertising campaigns.
With the exception of Google Ads traffic (which will automatically populate the campaign name), Google Analytics will not report on campaigns by default. You need to use UTM parameters to categorize marketing campaign data.
So:
Session Campaign Table
In the Session campaign data above, only two rows represent marketing campaigns: