// Tracking and data
What Is Google Analytics 4 (GA4) and How to Read Its Data
GA4 records behaviour as events, not as page visits. Read the data model, the reports that answer business questions, and the new AI Assistant channel.
GA4 records behaviour as events. Every action is one event with a name and parameters. Page views, clicks, and purchases use the same model. Universal Analytics used sessions and page views as the main unit, so old reports do not move across one for one.
The data model: events and parameters
The event name answers "what happened". The parameters answer "with which details". Example: a purchase event with value, currency, and items.
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Fix the event names before the install. A name that changes midway splits the history into two pieces.
Reports that answer business questions
| Question | Report | What you read |
|---|---|---|
| Where do people come from? | Acquisition | Default channel group and traffic source. |
| Which pages do people read? | Engagement | Pages and screens, engagement time. |
| What produces revenue? | Monetisation | Purchase events and their value. |
| Where do people stop? | Exploration | FunnelFunnelThe order of stages a buyer passes, from meeting you to paying you.Open the glossary exploration between events. |
The AI Assistant channel in traffic reports
Google added an AI Assistant channel to the Default channel group. Visits from AI assistants such as ChatGPT, Gemini, and Perplexity no longer mix into Referral. The change lets you read the contribution of AI answers on its own.
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Install mistakes that repeat
- Event names mix upper and lower case. GA4 treats case as different names.
- The purchase value arrives as text. The
valuefield must be a number. - Internal traffic filters are missing, so the team visits count as customers.
- Data retention stays on the default, so long analysis loses history.
Questions and answers
Can GA4 replace the Meta Ads report? No. GA4 measures behaviour on your site. Meta measures the result of its own ads. The two use different attributionAttributionHow a system decides which ad or channel receives the credit for 1 sale.High clicks, low sales: the tracking gap windows, so a gap between them is normal.
Why is the GA4 number lower than the Meta Ads number? Common causes are cookie refusals, script blockers, and different attribution windows. Compare the direction of change between periods, not the absolute number between systems.
Does GA4 require Google Tag Manager? No. You can install the GA4 tag directly. Google Tag Manager helps when the number of tags grows and several people edit them.
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Official sources
We checked every claim on this page against the documents below on 11 September 2026. Open the source before you change a live system.
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