TopolearnKnowing what GA4 measures and how it differs from the old product tells you what its numbers mean.
Google Analytics 4 (GA4) is the current version of Google Analytics. You add a small JavaScript tag to your website (or the Firebase SDK to an app), the tag sends events to Google, and GA4 turns those events into reports about who visits, where they came from, what they did and whether they converted.
It replaced Universal Analytics (UA). UA stopped processing data on 1 July 2023 and its historical data was deleted in 2024, so anything you read about "goals", "bounce rate as a top metric" or "hit types" describes the old product. The differences matter:
- UA stored pageviews, events and transactions as different hit types. GA4 stores everything as an event with parameters: a page view is just the
page_viewevent. - UA was session-centric; GA4 is user- and event-centric, and can tie web and app data together in one property.
- GA4 reports come in two families: curated standard reports and the free-form Explore workspace for ad-hoc analysis.
- GA4 uses machine-learned modelling (for consented-but-missing data and predictive metrics) rather than only raw counts.
GA4 is free for most sites; a paid tier, Analytics 360, raises limits (sampling thresholds, retention, export volume). Everything in this course applies to the free tier unless noted.
People use GA4 to answer questions like: which campaigns bring buyers, which landing pages lose people, where users drop out of a signup flow, and how many of last month's new users came back.
Remember
- GA4 is event-based: every interaction, including a page view, is an event
- Universal Analytics is dead since July 2023; its vocabulary (goals, hit types) does not apply
- Two ways to look at data: standard reports and Explore