Digital marketing glossary

What is an event in GA4?

Written and reviewed by L.K. Monu Borkala · Updated 7 November 2026

Definition

In Google Analytics 4 (GA4), an event is any interaction or occurrence that GA4 records, such as a page view, scroll, outbound click, file download, form submission or purchase. GA4 builds all of its reports from events, so understanding them is the first step to measuring what visitors actually do on your website or app.

How it works

GA4 events fall into four groups. Automatically collected events, such as first_visit and session_start, need no setup. Enhanced measurement events, such as page_view, scroll, outbound clicks and file_download, are switched on in your data stream settings. Recommended events, such as generate_lead, sign_up and purchase, have names and parameters that Google suggests so its reports work well. Custom events are ones you define yourself, often through Google Tag Manager. Each event can carry parameters, which are extra details like the page address or order value. You can mark your most important events as key events, which GA4 used to call conversions.

Example

Imagine a cooking class studio in Hyderabad whose GA4 shows plenty of page views but nothing about bookings. Using Google Tag Manager, the owner sends a generate_lead event when someone submits the class enquiry form, with a parameter for the class name, and a custom whatsapp_click event when someone taps the WhatsApp button. She marks both as key events. Now she can see that the ₹1,800 biryani masterclass page brings the most WhatsApp enquiries, and she can use those signals in her ads.

An illustration: the business and the rupee figures are made up to show how the idea works.

Common mistake

Creating dozens of custom events with messy names like 'Click1' and 'btn-whatsapp-new', then forgetting what each one means. Use recommended event names where they fit and a clear naming rule for the rest. Another mistake is marking every event, including page_view and scroll, as a key event, which makes your conversion numbers meaningless.