Google Analytics 4 launched on October 14, 2020. Google initially positioned it as optional, running alongside Universal Analytics, but that changed when they announced Universal Analytics would sunset. Standard UA properties stopped collecting data July 1, 2023, and UA 360 followed on October 1, 2023. GA4 represents a complete rebuild rather than an incremental update. It uses an event-based model instead of session-based tracking, combines web and app data in one property, and relies heavily on machine learning for insights and predictive metrics. The shift forced every website owner to migrate or lose historical tracking continuity. The transition created major headaches. GA4's interface differs drastically from Universal Analytics, reports don't match 1:1, and many features agencies relied on disappeared or changed. Custom reporting requires learning Explorations instead of the old Custom Reports interface. Funnel visualization, real-time user flow, and certain ecommerce reports all work differently now. At Ottawa SEO, we started migrating client properties in early 2022 once GA4 stabilized enough for production use. Running both platforms in parallel for 12–18 months let us build historical data in GA4 while still relying on UA for accurate reporting. That parallel period was critical because GA4 data from day one is sparse compared to a mature UA property. The forced migration taught us that GA4 suits different use cases better. It excels at cross-device user journeys and privacy-compliant tracking without heavy cookie dependence. But if you need granular session analysis or prefer straightforward reporting without building custom explorations, the learning curve is steep. If you're still clinging to old UA data exports, you have until July 2024 (standard) or October 2024 (360) to download historical reports before Google deletes them permanently. After that, whatever you didn't export is gone. For Canadian businesses tracking CRA-relevant conversion data or multi-year customer acquisition costs, losing that history matters more than Google acknowledged during the rollout.