What is Google Analytics 4 (GA4)?

Google Analytics 4: definition and meaning

GA4 measures how visitors use a website or app: where they come from, which pages they view, and whether they complete a desired action, such as sending an inquiry. It replaced Universal Analytics, whose data processing ended in July 2023; for the paid 360 version, that happened a year later.

The key difference: instead of page views and sessions, GA4 counts events. Every interaction—page view, scroll, click, form submission—is an event with parameters. This makes analysis more flexible but requires a clean setup. Figures from old reports cannot be compared one-to-one because of the different data model.

How GA4 works

A code snippet or Google Tag Manager sends events to GA4. Page views and scroll depth, for example, are captured automatically; custom events such as “contact form submitted” have to be defined. The more precisely events are described, the more meaningful the reports become. Important events are marked as key events (formerly “conversions”). Typical analyses:

• Acquisition: which channels do visitors come from—search, social media, newsletter, advertising?
• Engagement: which pages and content are used?
• Key events: how many inquiries, purchases, or appointment bookings result?
• Explorations: free-form analyses, funnels, and user paths
• Linking with Search Console, Google Ads, and BigQuery

Real-world example: comparing channels in an online store

An online retailer uses a newsletter, Google Ads, and SEO. With properly set UTM parameters and a key event for completed purchases, GA4 shows, for instance, that the newsletter brings fewer visitors but a higher purchase rate than paid ads. The budget can be distributed accordingly.

Without defined events, only the visitor count would be visible—and hardly a basis for decisions. Linking with Search Console additionally shows which search queries led to the visits. On that basis, you can decide where additional content or ad budget promises the greatest effect.

Benefits, limitations, and common mistakes

GA4 is free in the standard version, works across channels and devices, and can be connected to Google Ads. Limitations: the interface is considered an acquired taste, event data for explorations is stored for only two months by default (adjustable up to 14 months), and without consent data is missing. With Consent Mode, GA4 can estimate gaps through modeling when consent is denied. Data protection: under the TDDDG and the GDPR, consent generally has to be obtained. Typical mistakes:

• No key events defined, only visitor numbers
• Internal traffic from employees and agencies not filtered out
• Inconsistent UTM parameters, so channels are attributed incorrectly
• Tracking fires before consent is given
• Data retention left at the default setting

What companies should look out for

Before setup, decide which goals count and derive events from them. Obtain consent through a consent banner, supplement your privacy policy and data processing agreement, and have the configuration reviewed for data protection compliance. Nano Concepts sets up GA4 together with Tag Manager and a consent solution and builds reports around your goals.