The GA4 events model, explained for people who aren't analysts

GA4 confuses people coming from Universal Analytics because it threw out the old model entirely. Here is the whole thing in one read.

Everything is an event

In GA4 there are no separate "pageviews vs events vs goals." Everything is an event. A page load is a page_view event. A purchase is a purchase event. A click is a click event. Each event carries parameters — key/value pairs — describing it.

The four kinds of events

• Automatically collected — GA4 fires these on its own (first_visit, session_start).
• Enhanced measurement — toggle-on events for scrolls, outbound clicks, site search, and video, with no code.
• Recommended — Google-defined names with expected parameters (purchase, add_to_cart, sign_up). Use these names exactly.
• Custom — your own event names for anything the above don't cover.

⚠️ Warning: The most common GA4 mistake: inventing a custom name when a recommended one exists — e.g. buy instead of purchase. Google's ecommerce reports and audiences only understand the recommended names, so a clever synonym silently drops out of the reports that matter.

Parameters and custom dimensions

An event alone ("purchase") is not useful without detail. Parameters carry it: value, currency, transaction_id, items. To report on a custom parameter you must register it as a custom dimension in GA4 admin — otherwise it is collected but not queryable.

Key events (formerly conversions)

Any event you mark as important becomes a "key event" — what GA4 used to call a conversion. That is how GA4 knows which events represent business value. (Google renamed this in 2024–2026; see our post on the Conversions → Key events rename for the API fallout.)

Why the model trips people up

Because it is more flexible AND less forgiving. Flexible: you can track anything as an event. Unforgiving: nothing validates your names or parameters, so a typo (purchace) or a missing value param produces a report that looks fine but sums to nothing. Run the free audit to check whether your key events are landing with the right parameters.