GA4 is Google’s event-driven analytics platform for websites and apps. Instead of sessions with pageview-centric hits, everything is an event with attached parameters. That shift makes GA4 better at cross-device tracking, funnels, and product analytics, while still supporting classic web metrics like sessions, users, and conversion rate.
In practical terms, GA4 stores a stream of user interactions (page_view, scroll, add_to_cart, purchase). Each event can carry rich context via event parameters (e.g., value, currency, item_id). You mark some events as conversions to measure outcomes that matter to the business.
How GA4 works (in one picture)
| Building block | Meaning | Example |
|---|---|---|
| Event | Atomic interaction | purchase |
| Parameters | Key–value context for an event | value=59.90, currency=USD, coupon=SUMMER10 |
| User properties | Stable traits for a user | plan=premium |
| Session | Time-bounded group of events | Campaign visit from email |
| Conversion | Event flagged as success | sign_up, purchase |
Mini example: a shop recordspurchase with value=59.90, currency=USD, items=[{id:"sku_123", qty:1}]. GA4 attributes that conversion to the active campaign (see UTM parameters) and includes it in reports and Exploration workbooks.
Key metrics & quick math
- Engagement rate shows quality of traffic:
Engagement Rate = Engaged Sessions / Sessions. See engagement rate. - Conversion rate at the session level:
CR = Conversions / Sessions × 100%. See conversion rate. - Revenue analysis often pairs with AOV and funnel steps; use attribution models to understand where credit lands.
Implementation notes
- Send consistent events via your tag manager and the Data Layer; name events/parameters with a clear schema (
verb_object, lowercase, underscores). - Respect privacy. Configure Consent Mode; expect modeled data when identifiers are limited.
- For analysis, start with standard reports, then build funnels, cohorts, and segments in Explorations for product and marketing questions.