What is the definition of "first visit" event on GA4

Question

According to official document of Google. It says that

the first visit event is triggered when the first time a user visits a website or launches an Android instant app with Analytics enabled

How do they know the user is first visit or not. If users who had been use the web-site also caliculate as first_visit if they cleared browser cash?

I would appreciate if you would let me know.

Thank you.

References: https://support.google.com/analytics/answer/9234069?hl=en#:~:text=deferred_analytics_collection%2C%20reset_analytics_cause%2C%20engagement_time_msec-,first_visit,-(app%2C%20web)

Answer 1

speaking about the first_visit event, the first thing to know is: The first_visit event references only to the first visit according to the look back window (default 30 days) https://support.google.com/analytics/answer/10597962?hl=en#zippy=%2Cin-this-article That's a confusion I stumbled on lately.

And yes as you said, if the user is accessing the site from different devices or clear the browser cache and isn't logged in Chrome Browser, this event wouldn't be suitable for the first visit because it's based on the ClientID (aka user_pseudo_id in BigQuery). This means this one person would count as multiple visitors.

To identify the user trough the whole journey there is a new ID in GA4 called UserID, this ID is not generated by Google, you have to setup for your page individually, based on existing identifier you have e.g. User Account. https://www.analyticsmania.com/post/google-analytics-4-user-id/

Hope this helps a bit :)