Google Analytics 4 is Google's current analytics platform that fundamentally changed how we measure user behavior compared to Universal Analytics. Instead of organizing data around sessions and pageviews, GA4 uses an event-based model where every interaction—page loads, clicks, video plays, form submissions—is tracked as an event with parameters. This makes it far more flexible for tracking modern user journeys across devices and platforms. The platform was built for a privacy-first world. GA4 doesn't depend entirely on third-party cookies and uses Google's machine learning to fill data gaps from users who opt out of tracking. It includes features like predictive metrics (purchase probability, churn probability) and anomaly detection that Universal Analytics never had. The cross-platform tracking is also native—you can measure a user's journey from your website to your iOS app under one property, something that required complex workarounds before. Key differences from Universal Analytics: - Event-based tracking instead of hit-based (sessions, pageviews, events as separate types) - Built-in e-commerce tracking with item-scoped parameters - Engagement metrics like engaged sessions replace bounce rate as the primary indicator - Automatic enhanced measurement for scrolls, outbound clicks, site search, video engagement - BigQuery export available on the free tier, not just Analytics 360 - Different report interface focused on exploration and custom reports At Ottawa SEO, we migrated all 500+ properties to GA4 before the July 2023 deadline because waiting meant losing year-over-year data continuity. The learning curve is real—GA4's interface is less intuitive than Universal Analytics, and standard reports show fewer metrics by default. You need to build custom explorations for deeper analysis. The data model is more powerful but requires understanding events and parameters to use effectively. If you're setting up GA4 now, spend time configuring custom events and conversions upfront rather than relying only on automatic tracking. The platform rewards proper implementation far more than UA did.