Google Analytics 4, explained
Learn the measurement model first, then move through acquisition, engagement, campaign tracking and troubleshooting in a practical order.
Recommended reading order
Eight focused articles, each answering one common analytics question.
What is Google Analytics 4?
GA4 is Google's event-based measurement product for understanding activity across websites and apps. It turns collected interactions into reports, but it is neither a perfect census of people nor an automatic business strategy.Users vs sessions in GA4
Users describe measured people or devices; sessions describe periods of interaction. One measured user can start several sessions, so the numbers answer different questions.Events and parameters in GA4
An event says something happened. Parameters describe what happened. A small, consistent event model is more useful than a long list of vaguely named events.Dimensions vs metrics in GA4
A dimension describes what kind of thing a row represents. A metric supplies a number for that row.Source, medium and channels in GA4
Source identifies an origin; medium describes the acquisition method; campaign groups a promotion; channel groups apply rules that make traffic easier to scan.Engagement and key events in GA4
Engagement metrics describe measured interaction under GA4's rules. Key events identify actions important to your organisation. Neither has one universal target.UTM parameters for GA4
UTM parameters are campaign labels added to destination URLs. They help GA4 classify manually tagged traffic when they are complete and consistently named.How to check if GA4 is working
Verify collection from the browser outward: tag, consent, request, Realtime and debug reports. Check one layer at a time before changing the implementation.
GA4 is Google's event-based measurement product for understanding activity across websites and apps. It turns collected interactions into reports, but it is neither a perfect census of people nor an automatic business strategy.Users vs sessions in GA4
Users describe measured people or devices; sessions describe periods of interaction. One measured user can start several sessions, so the numbers answer different questions.Events and parameters in GA4
An event says something happened. Parameters describe what happened. A small, consistent event model is more useful than a long list of vaguely named events.Dimensions vs metrics in GA4
A dimension describes what kind of thing a row represents. A metric supplies a number for that row.Source, medium and channels in GA4
Source identifies an origin; medium describes the acquisition method; campaign groups a promotion; channel groups apply rules that make traffic easier to scan.Engagement and key events in GA4
Engagement metrics describe measured interaction under GA4's rules. Key events identify actions important to your organisation. Neither has one universal target.UTM parameters for GA4
UTM parameters are campaign labels added to destination URLs. They help GA4 classify manually tagged traffic when they are complete and consistently named.How to check if GA4 is working
Verify collection from the browser outward: tag, consent, request, Realtime and debug reports. Check one layer at a time before changing the implementation.
Plain-English glossary
Use these definitions as a map, then open the relevant article for context and examples.
- Active user
- A user GA4 considers engaged during the selected period.
- Session
- A period of interaction that starts when no session is already active.
- Engaged session
- A session lasting longer than 10 seconds, containing a key event, or reaching at least two page or screen views.
- Event
- A recorded occurrence such as a page view, click or sign-up.
- Parameter
- Extra information attached to an event.
- Dimension
- A descriptive attribute used to group data.
- Metric
- A number that can be counted, summed or calculated.
- Key event
- An event marked as especially important to the organisation.
- Source
- The publisher or origin associated with traffic, such as google or a newsletter.
- Medium
- The broad acquisition method, such as organic, referral, email or cpc.
- Campaign
- A name used to group related promotional traffic.
- Channel group
- A rule-based category that groups traffic sources.
- Landing page
- The first page viewed in a session.
- Direct
- Traffic for which Analytics has no usable referring or campaign source.
- Realtime
- A report for recent activity and basic implementation checks.
- DebugView
- A development report for inspecting debug-mode events and parameters.
- Exploration
- A flexible analysis workspace beyond standard reports.
- (not set)
- A value shown when Analytics has no value for a dimension in that context.
Before the measured visit
Search Console explains how pages appear and perform in Google Search. GA4 explains measured behaviour after arrival; their totals use different systems and should not be expected to match.
Learn Google Search Console →