Definition
What is GA4 (Google Analytics 4)?
GA4 (Google Analytics 4) is Google's audience measurement tool, offered in a free version. It records what visitors do on a website or an app as events: a page view, a form submitted, a purchase. It is the only place where paid, organic, direct, email and referral traffic are compared on the same rule. Advertising bids, for their part, are driven by each platform's own tags.
Measurement built on events
Every interaction becomes an event, with parameters: the page, the hostname, the value of a purchase. The events that matter to the business (a qualified form, a call, a sale) are declared as key events: they are GA4's conversions.
GA4 replaced Universal Analytics, which stopped processing data on July 1, 2023. In the free version, explorations go back no further than the data retention period chosen: 2 or 14 months. To compare one year with another, retention is set to 14 months from the start, because it does not apply retroactively.
What GA4 does and what it should not do
GA4 serves analysis and audiences. It tells you where visitors come from, what they do on the site and which channels lead to enquiries. Site traffic and conversion are read in GA4; sales and revenue are taken from your order system or your CRM.
Driving Google Ads bids with conversions imported from GA4 distorts the automation: each platform's native tag is built for that job. Importing GA4 into a platform that already has its own tag can also count the same enquiry twice.
What distorts GA4 reports
- Inflated direct traffic. A visit that arrives without a UTM parameter or a referring address is classified as direct. Since the launch of GPT-6, in October 2026, clicks from ChatGPT arrive this way.
- Spam. The measurement ID (the property's "G-" code) can be read in the code of your pages: anyone can use it to send fake visits. The hostname filter blocks part of it.
- Cookie refusals. Visitors who refuse disappear from your reports if nothing is planned. Google's Consent Mode models part of them, under certain volume conditions.
- Sales made elsewhere. A sale closed by phone, through a quote or at a checkout outside your site does not appear in GA4.
Who owns the account
The GA4 property is created in your company's name, with an internal email address. The agency is then invited with the access level it needs. Your data history thus stays with you when you change providers.
Fictional example: from October 9, 2026, an online store sees its traffic from ChatGPT drop in GA4 while its direct traffic rises by the same amount. Its total sales do not move. This is probably a measurement problem rather than a loss of visibility: since GPT-6, clicks from ChatGPT arrive without a parameter or a referring address.
We read GA4 as the place where channels are compared on the same definition of a sale: that is what lets us set a dollar of advertising beside a year of SEO. Without that common base, paid looks like the only channel producing leads, because it is the only one being counted.
We leave bidding to each platform's native tags. Before switching on a filter that deletes data for good, we check the hostname of your sale and lead events.
Not to be confused with
- Google Tag Manager
- Google Tag Manager is the container that fires the measurement tags on the site, GA4's included. GA4 receives the data and analyzes it.
- Search Console
- Search Console shows how your site appears in Google Search before the click: queries, impressions, positions. GA4 measures what visitors do once they are on the site.
Related concepts
- Conversion
- Data-driven attribution
- Consent gap
- Hostname
- Server-side tagging
- Enhanced conversion
- AI-referred traffic
- Executive dashboard
Further reading
- GA4 spam traffic: how to spot and block it with the hostname filter
- Since GPT-6, visits from ChatGPT show up as direct traffic in GA4
- Consent and measurement: understanding Google Consent Mode's limits
- Conversion tracking: connecting your campaigns to actual sales
- Multi-touch attribution: which models are still available in Google's tools?
Related services
Frequently asked questions
Do I need GA4 if Google Ads already counts conversions?
Yes, but not for the same job. Native tags serve bidding. GA4 serves analysis, because it is the only place where paid, organic and direct traffic are compared on the same rule.
Why is my direct traffic rising in GA4?
GA4 classifies a visit as direct when it receives neither a UTM parameter nor a referring address. Links without UTM tags, clicks from ChatGPT since GPT-6 or fake traffic can inflate that line. Before drawing a conclusion, compare the direct curve with the curves of the channels that are falling.
Who should own our GA4 account?
Your business. The account is created in your name with an internal email address, then the agency is invited with the access level it needs. The history stays with you if you change providers.
