Total Users is the number of all unique users in GA4 who visited during the selected period. It is broader than active users as it is independent of engagement or not, and the difference between the two metrics evaluates the quality of a visit.
A new user is a user who has visited GA4 for the first time during the selected period. Because it is identified based on client ID, the same person may be re-counted when the device or browser is changed, and is a key indicator for evaluating the performance of new traffics by channel.
Average engagement time per session in GA4 is total measured engagement time divided by the total number of sessions. Its denominator is not limited to engaged sessions.
The number of sessions is the total number of visits in the selected period in GA4. Unlike UA, there is no automatic separation when midnight or campaign changes, so it is less than UA for the same period, and the quantity and quality of visits are evaluated along with the number of engaged sessions.
Traffic Acquisition is a report in GA4 that analyzes the intake channel for each session. Since it also includes the recent visit path of returning users, it is suitable for understanding the short-term session performance of campaigns and channels.
First User Source is the source of a user's first visit in GA4. It does not change even if the return visit path changes afterward, and is used to analyze new user acquisition channels.
Source/Medium is the primary channel dimension in GA4 that combines traffic source and delivery method. 'google/organic' is Google's organic search, and 'google/cpc' shows at a glance where and how it came from, like Google advertisements, and is the basic unit of channel performance analysis.
Direct traffic is sessions whose origins cannot be determined by GA4. In addition to simple direct input, causes include non-UTM tagging, referrer loss, and in-app browser restrictions. If the rate is high, the UTM tagging status must be checked.
The UTM source is the ?utm_source= parameter attached to the URL, allowing GA4 to accurately identify which site or channel the traffic is coming from. The source is specified like naver, google, and instagram, and it is standard to use it with utm_medium (channel type) and utm_campaign (campaign name).
For UTM medium, the inflow method (cpc, organic, email, etc.) is recorded in GA4 with the utm_medium parameter of the URL. This is a core criterion for GA4 channel group classification, so if values are not unified within the team, channel data will be scattered.