In this guide
- GA4 treats every interaction as an event, including page views. Events carry parameters that describe them.
- There are four kinds: automatically collected, enhanced measurement, recommended and custom. Use a recommended name when one exists.
- Mark only the few events that matter to the business as key events. A short, consistent event list beats a long messy one.
Universal Analytics counted sessions and pageviews and used categories, actions and labels for everything else. Google Analytics 4 replaced all of that with one idea: an event with parameters. A page view is an event. A purchase is an event. A click on your phone number is an event. Understanding the four kinds of event and how to name them is the single most useful thing you can learn about GA4. This page covers them, the limits and a way to plan them. For sending them from a server, see GA4 advanced tag for server GTM.
The anatomy of an event
An event has a name (for example purchase) and up to 25 parameters (for example value, currency, transaction_id). Parameters give an event its meaning. A parameter becomes useful in reports once you register it as a custom dimension or custom metric; until then it is collected but only visible in some views such as DebugView and BigQuery.
Works with your stack
Grab a logo and throw it. These are the tools Open Tracked already talks to.
The four kinds of event
Automatically collected
Sent as soon as the tag is installed: first_visit, session_start, page_view, user_engagement, and app events such as app_open. You cannot turn most of these off.
Enhanced measurement
Switchable in the data stream settings: scroll (90% depth), click (outbound links), view_search_results, video_start, video_progress, video_complete, file_download and form_start / form_submit. Fast to turn on, but check that they really fire on your site.
Recommended events
Names Google defines with set parameters: add_to_cart, begin_checkout, purchase, generate_lead, sign_up, login and many more. Use them whenever your action matches, because GA4 reports and Google Ads features understand them.
Custom events
Anything else you name yourself, for example quote_requested. Use them when no recommended event fits.
Limits to know before you plan
| Item | Standard property limit | Why it matters |
|---|---|---|
| Distinct event names | 500 per property | Dynamic names such as click_button_red can fill this fast |
| Parameters per event | 25 | Keep the useful ones, drop the rest |
| Event name length | 40 characters | Names are cut or rejected after that |
| Parameter value length | 100 characters | Long text, such as URLs with query strings, is cut |
| Custom dimensions (event scope) | 50 | Register only the parameters you will report on |
| Key events | 30 per property | More than a handful loses its meaning |
Google adjusts limits from time to time, and 360 properties get higher ones, so confirm the current numbers in the GA4 help pages before you build a large plan.
Orders from your store, back to the ad that earned them
Your store sends the order once. Open Tracked passes it on to each ad platform, cleaned and deduplicated.
Naming rules that save you later
- Use lower case with underscores:
generate_lead, notGenerate Lead. GA4 names are case sensitive. - Start with a letter. Do not use reserved prefixes such as
ga_,google_orfirebase_. - Describe the action, not the page:
form_submitwith aform_nameparameter, notcontact_page_form_submit. - Use one recommended name instead of inventing a similar one.
purchasealready exists, so do not createorder_complete. - Never put personal data in a name or parameter. E-mail addresses, phone numbers and names in GA4 break Google's terms.
Key events
A key event (called a conversion before 2024) is an event you tell GA4 matters to the business. Mark purchase, generate_lead and perhaps sign_up. Key events feed the conversion reports and can be imported into Google Ads. Marking ten events as key dilutes the signal; keep the list short.
A tracking plan in one table
| Business question | Event | Key parameters |
|---|---|---|
| Did they buy? | purchase | transaction_id, value, currency, items |
| Did they start to buy? | begin_checkout | value, currency, items |
| Did they show product interest? | view_item, add_to_cart | item_id, item_name, price |
| Did a lead come in? | generate_lead | form_name, value (if you can estimate one) |
| Did they search? | search | search_term |
Write this list before touching Tag Manager. It becomes your data layer specification and the checklist for testing.
Testing events
- Open GA4 DebugView and your site in the same browser with the debug extension or GTM Preview on.
- Perform the action. The event should appear within seconds with all parameters.
- Check the value of every parameter, not only the event name.
- Wait a day and confirm the event is in the standard reports. Custom dimensions only fill from the day they are registered.
Where server-side tagging helps
The browser tag sends the event to your own tagging address. The server container can add fields, remove fields and send the same event on to other tools. With Open Tracked, the Device Info and Visitor Location power-ups add the operating system, browser and country as parameters, which saves you building them in the page. See server-side tracking events.
Checklist for a clean GA4 event set
Typical event mistakes
purchase on every reload, or the browser and server both send it without a shared ID.transaction_id and let GA4 deduplicate, and fire the event only once per order.Check your tracking in one pass
This is an example. Run the check on your own site to see where yours stands.
Frequently asked questions
What is the difference between an event and a key event?
An event is any recorded interaction. A key event is one you mark as important to the business, so GA4 counts it as a conversion.
How many events can GA4 have?
A standard property allows 500 distinct event names, with up to 25 parameters on each event. Check the current limits in Google's documentation.
Should I use enhanced measurement or my own tags?
Turn on enhanced measurement for a quick start, then replace any event that does not fire correctly with your own tag.
Why are my custom parameters missing from reports?
Register them as custom dimensions or metrics. Until then they show only in DebugView and BigQuery.
Can I rename events later?
You can create a new event from an existing one in GA4, but history is not renamed. Plan names first.
Do I need spreadsheets to read my results?
No. Once tracking is live, the Open Tracked analytics shows spend, revenue, ROAS and profit, and you can ask Ari, the built-in AI assistant, questions about your own numbers in plain words. Ari's allowance depends on your analytics plan.
Is Open Tracked different from Open Track or Open Space Track?
No. Open Tracked is the official name of our server-side tracking platform, and the website is opentracked.io. Many people search for it as Open Track, OpenTrack or Open Space Track. All of them lead to the same product: server-side Google Tag Manager hosting, first-party analytics and a CRM pipeline.
Fix your tracking at the source
Open Tracked hosts your server-side Tag Manager, keeps first-party cookies alive and shows what each ad is really worth.
The Open Tracked team
We build Open Tracked: server-side tracking hosting, analytics and the tools around them, for stores that spend on ads. Questions about this guide, or an idea for the next one?
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