Google Analytics 4 is Google's current analytics platform that fundamentally changed how website and app data gets collected and reported. Unlike Universal Analytics, which organized data around sessions and pageviews, GA4 uses an event-based model where every interaction—pageviews, clicks, video plays, form submissions—is tracked as an event with parameters. This makes it far more flexible but also requires a different mental model when setting up tracking. The core shift is cross-platform measurement. GA4 properties can collect data from websites and mobile apps in a single property, tracking users across devices using Google signals and your own user IDs. Universal Analytics kept web and app data separate. GA4 also emphasizes privacy by design, with no IP address logging by default, built-in consent mode, and data retention controls that matter more under Canadian privacy law (PIPEDA) and similar regulations. GA4 uses machine learning to fill gaps from users who don't consent to cookies, predict future actions like purchase probability, and surface insights automatically. The reporting interface is completely different—fewer pre-built reports, more reliance on Explorations (custom reports) and the real-time interface. Standard reports focus on user lifecycle stages: acquisition, engagement, monetization, retention. For our portfolio, we migrated all 500+ domains before the July 2023 deadline when Universal Analytics stopped processing hits. The transition required relearning reporting paths, rebuilding custom dashboards in Looker Studio, and fixing event tracking that didn't auto-migrate cleanly. Conversions work differently too—you mark events as conversions instead of setting up goals, and there's no direct equivalent to UA's goal funnels in standard reports. The biggest gotcha is historical data. GA4 doesn't import your Universal Analytics history, so year-over-year comparisons broke for everyone in 2023. You also need to actively configure enhanced measurement settings and custom events because GA4's auto-tracking misses nuances like outbound link clicks to specific domains or form interactions beyond generic button clicks. For Canadian businesses especially, make sure your data retention is set to 14 months maximum (the longest GA4 allows) and your consent mode is configured if you serve EU or Quebec traffic.