Google Analytics 4 Event Tracking Tutorial（2025）

Table of Contents

Google Analytics 4 is event-driven, all data and behaviors are tracked through events, but event tracking also has some limitations.

Event Limit

	Web	APP
Distinctly named events	Unlimited	500
Events per User per day	Unlimited	500

Event Rules

Event = Event Name + Event Parameter

Event Name Rule

Event name is at most 40 bytes
Event names are case sensitive. For example, my_event and My_Event are distinct events.
Event names can include English and non-English words and letters.
Do not use reserved prefixes and event names.
Event names must start with a letter. Use only letters, numbers, and underscores. Don’t use spaces.

Event Parameter Rule

Each event can set up to 25 Event Parameters
Event Parameters can be divided into Default (built-in) Event Parameters and Custom Event Parameters.
- Default Event Parameters: also called Built-in event parameters, are what all events have by default.
  - For Web, there are 5 default event parameters:
    - page_location（No more than 1000 characters）
    - language
    - page_referrer （No more than 420 characters）
    - page_title （No more than 300 characters）
    - screen_resolution
  - For APP, there are 3 default event parameters:
    - app_version
    - firebase_screen_id
    - firebase_screen_class
- Custom Event Parameters: It is the user-defined event parameter, which can be divided into two types:
  - Event-scoped custom dimensions: which is a character-type event parameter, has a maximum of 40 characters and a limit of 50
  - Event-scoped custom metrics: which is a numeric-type event parameter, has a maximum of 100 characters/length and a limit of 50
- Event parameters need to be set in GA4 Custom Definitions before they can be used

Types of events

Events can be divided into four types:

Automatically Collected Events
Enhanced Measurement Events
Recommended Events
Custom Events

Automatically Collected Events

Automatically Collected Events (aka Automatic Events) are automatically collected by the system without additional settings, as long as you have the gtag.js installed, and basic user interactions with your website, for example: page_view.

Automatically Collected Events include:

first_visit： the first time a user visits a website
page_view：each time the page loads or the browser history state is changed by the active site
session_start：when a user engages the website, A session ID and session number are generated automatically with each session and associated with each event in the session
user_engagement：when the app is in the foreground or webpage is in focus for at least one second

Automatically Collected Events cannot be disabled, and do not count towards the 500 event limit.

Learn More：Google Analytics 4 Event Tracking ①——Automatically Collected Events

Enhanced Measurement Events

Enhanced Measurement Events are built-in events, just need to be enabled in the web data stream, No code changes are required, and Google Analytics tag starts sending events right away.

Enhanced Measurement Events include 6 type :

Actions	Enhanced Measurement Events	Triggered…	Parameters
Page views	page_view	each time the page loads or the browser history state is changed by the active site This event is collected automatically. You cannot turn off collection.	page_location 、page_referrer
Scrolls	scroll	the first time a user reaches the bottom of each page (i.e., when a 90% vertical depth becomes visible)	No parameters.
Outbound clicks	click	each time a user clicks a link that leads away from the current domain By default, outbound click events will occur for all links leading away from the current domain. Links to domains configured for cross-domain measurement will not trigger outbound click events.	link_classes link_domain link_id link_url outbound (boolean)
Site search	view_search_results	each time a user performs a site search, indicated by the presence of a URL query parameter By default, the event is triggered based on the presence of one of the following 5 parameters(q、s、search、query、keyword) in the URL，you can customize up to 10 parameters	search_term, optionally ‘q_<additional key=””>’ (where <additional key=””> matches an additional query parameter you specify to be collected under advanced settings)
Video engagement	video_start video_progress video_complete	For embedded videos that have JS API support enabled, the following events are triggered: video_start： when the video starts playing video_progress： when the video progresses past 10%, 25%, 50%, and 75% duration time video_complete ：when the video ends	video_current_time video_duration video_percent video_provider video_title video_url visible (boolean)
File downloads	file_download	Triggered when the user downloads the following file: pdf\|xlsx?\|docx?\|txt\|rtf\|csv\|exe\|key\|pp(s\|t\|tx)\|7z\|pkg\|rar\|gz\|zip\|avi\|mov\|mp4\|mpe?g\|wmv\|midi?\|mp3\|wav\|wma	file_extension file_name link_classes link_domain link_id link_text link_url

Learn More : Google Analytics 4 Event Tracking ②——Enhanced Measurement Events

Recommended Events

Recommended Events is Google’s pre-defined event name and event parameters based on the industry. You need to send data according to the predefined event name and event parameters before you can see the data in GA4.

Learn More : Google Analytics 4 Event Tracking ③——Recommended Events

Custom Events

If you don't understand, You can leave a comment below.