In a previous article I talked about the Enhanced Measurement and commented that Google Analytics 4 automatically recorded a series of events.
By now, it will be clear to you that the main novelty GA4 has brought is that it is based on event measurement.
In case you are using the SDK (Apps) or the gtag.js code snippet, these events are logged automatically without the need to add any additional code when interacting with a web or application registered in a GA4 stream.
To view and manage these events, in the left panel of your GA4 property, go to the Events > all events option. From there you can, for example, define which events you want Analytics to consider as conversions or add additional parameters that you want to collect and measure, defining them as custom dimensions.

In addition, there are five parameters that are collected by default in all events, including custom events. These parameters are:
- language. Language of the browser or app.
- page_location. URL of the page.
- page_referrer. URL of the previous page.
- page_title. Title of the page.
- screen_resolution. Screen resolution.
Table of contents
Events that GA4 records automatically
Google Analytics 4 registers by default, in the case of web flows, three events (four if we include the page_view event) together with their parameters:
first_visit
This event is triggered the first time a user visits a website or starts an Android app with Google Analytics enabled. It does not collect additional parameters to those already discussed above.

session_start
This event is triggered when a user interacts with a website or application with Google Analytics enabled. As in the previous case, it does not collect additional parameters to those already discussed above.

user_engagement
This event is, at the moment, one of the least documented by Google. The only thing it currently says is that it is triggered ten seconds after the user visits a page without leaving it.
According to Google, it is also activated periodically, while the app is in the foreground, which leaves doubts as it does not clarify how often it is activated or whether it is only in apps or also on the web.
I have been testing with the Google Analytics DebugView and have come to the conclusion that it is triggered in the following scenarios:
- Approximately 10 seconds, but only on the first page visited.
- Before a new page_view event (change of page within the same website). In this case, the page_location parameter collects the value of the page that is being abandoned to go to the new one.
- When the browser tab is closed. The page_location parameter collects the value of the last page visited on the website before closing.

Looking at this, my conclusion is that this event is a timer that covers three scenarios:
- On the one hand to avoid bouncing, this could already be done before by setting a timer event and therefore launches that event after about 10 seconds, but apparently this happens when you land on the first page.
- On the other hand, measuring the total time spent on a page.
- And finally, measure the total time of the session.
Everything seems to indicate that this event comes to cover the problem that has existed until now to measure the total time spent on a page and the total time of a session. In the previous version of Google Analytics, this was truncated when closing the browser tab if a timer event had not been configured.
In addition to the default parameters, user_engagement collects an additional parameter engagement_time_sec which collects in milliseconds the time elapsed since the last user_engagement event (apparently).
page_view
I mentioned the page_view event earlier, but I didn't include it in these automatic events.
The truth is that this is an essential event within the analytics, however it is not in this classification because, for Google, it is an event included in the Enhanced Measurement. In the article in which I talk about this function incorporated into GA4 and which is activated by default, I describe this event in more detail.
Don't go yet
In short, just by enabling GA4 measurement we are measuring certain events on your website or app fully automatically. You can see all these events in the following Google article, both events that are measured on your website and events that are measured in your app. Actually the list of events that are measured automatically on the web are few. By the way, the events of the Enhanced Measurement events are included in this article.
I invite you to leave your impressions and/or doubts in the contact form and to suggest new topics that you would like me to cover in these tutorials. I will be happy to answer you by email and write in this blog.