linkutm Logo
Glossary Term

Google Analytics 4 (GA4)

glossary ga4 featured

Google Analytics 4 (GA4) is Google’s web and app analytics platform that measures user behavior using an event-based data model. GA4 replaced Universal Analytics as the only supported version of Google Analytics on July 1, 2023, when Universal Analytics stopped processing new data. It is free to use, tracks websites and mobile apps in a single property, and is the standard tool for measuring digital marketing performance.

Why GA4 Matters

GA4 is the default measurement layer for almost every marketing campaign that runs on a website or app. Every UTM-tagged link, paid ad click, organic visit, and conversion event eventually shows up inside a GA4 property. Marketing teams use it to attribute revenue to channels, measure campaign performance, build audiences for Google Ads, and report ROI to stakeholders.

The shift from Universal Analytics to GA4 was the largest change to web analytics in over a decade. Reports, dimensions, metrics, and even the definition of a session were rebuilt. Teams that ignore GA4 lose the ability to track campaigns, audiences, and conversions in Google’s ecosystem.

How GA4 Works

GA4 collects data through a tracking snippet (gtag.js) or Google Tag Manager on a website, and through the Firebase SDK in mobile apps. Every user interaction is recorded as an event with parameters attached to it.

The data flow looks like this:

  1. A user visits a site or opens an app.
  2. The tracking code fires events (page_view, click, scroll, purchase, custom events).
  3. Each event is sent to Google’s servers with parameters (page URL, source, medium, value).
  4. GA4 processes events, attributes them to a user and session, and stores them in its reports.
  5. Data appears in the GA4 interface and can be queried via BigQuery, the Data API, or Looker Studio.

A GA4 property contains one or more data streams. A data stream is a single source of data: a website, an Android app, or an iOS app. One property can hold all three, which is why GA4 is called a cross-platform analytics platform.

GA4 vs Universal Analytics

GA4 and Universal Analytics (UA) measure the same activity in very different ways. Knowing the differences prevents reporting mistakes when comparing old UA reports to new GA4 reports.

Difference Universal Analytics GA4
Data model Sessions and pageviews Events with parameters
Platforms Web only Web and apps in one property
Sessions End at midnight or on campaign change Do not end on UTM change
Bounce rate Single-page session percentage Inverse of engagement rate
Default attribution Last non-direct click Data-driven attribution
Conversions Goals (max 20) Key Events (unlimited)
Data retention Up to 50 months free 2 or 14 months free
Sampling Common in reports Standard reports unsampled
BigQuery export 360 only Free for all properties

Universal Analytics processed its last hit on July 1, 2023, for standard properties and July 1, 2024, for UA 360. Old UA data has been deleted from the interface, so historical comparisons need to be exported and stored elsewhere.

Key GA4 Reports and Concepts

GA4 organizes data into a small number of standard reports plus a free-form area called Explorations.

  • Realtime shows activity in the last 30 minutes.
  • Acquisition shows how users arrived (channel, source, medium, campaign). This is where UTM data appears.
  • Engagement shows pages viewed, events fired, and time spent.
  • Monetization shows revenue from purchases, ads, and subscriptions.
  • Retention shows how often users return.
  • Explorations is a drag-and-drop report builder for custom analysis (funnels, paths, segments, cohorts).

Two concepts cause the most confusion for teams new to GA4:

  • Key Events (renamed from Conversions in March 2024) are the events that count as business outcomes. Any event can be marked as a key event with one toggle.
  • Engagement rate is the percentage of sessions that lasted longer than 10 seconds, fired a key event, or had two or more page views. Bounce rate in GA4 is simply 100 minus the engagement rate.

GA4 and UTM Parameters

GA4 reads UTM parameters from the landing page URL on every session and populates five dimensions: Session source, Session medium, Session campaign, Session manual term, and Session manual ad content. Additional parameters (utm_id, utm_source_platform, utm_creative_format, utm_marketing_tactic) are also supported.

Consistent UTM tagging is the foundation of clean GA4 attribution. Unstandardized values like Facebook vs facebook vs FB show up as separate sources and fragment campaign reports. Validate UTM-tagged links before launch with linkutm’s free GA4 URL tester to confirm the parameters parse correctly.

How to Set Up GA4

A standard GA4 setup takes under an hour:

  1. Sign in to analytics.google.com and create an Account, then a Property.
  2. Add a Web data stream and copy the Measurement ID (G-XXXXXXXXXX).
  3. Install the gtag.js snippet in the site head or deploy the GA4 tag via Google Tag Manager.
  4. Confirm data is flowing in the Realtime report.
  5. Mark business-critical events as Key Events.
  6. Link Google Ads, Search Console, and BigQuery in Admin.
  7. Configure data retention to 14 months under Admin > Data Settings > Data Retention.
  8. Set up a marketing UTM convention so source, medium, and campaign values stay consistent.

Common GA4 Issues

Three problems account for most GA4 support requests:

  • Unassigned or (not set) traffic caused by missing or malformed UTM tags. See how to fix unassigned traffic in GA4 for a full diagnosis.
  • Conversion counts that don’t match Google Ads because GA4 uses data-driven attribution and Ads uses its own model.
  • Inflated session counts because GA4 sessions do not end on UTM change, so a single visitor reloading with a new tagged link no longer creates a new session.

Frequently Asked Questions

What does GA4 stand for?

GA4 stands for Google Analytics 4. The “4” indicates the fourth generation of Google Analytics, following Urchin, Classic Analytics, and Universal Analytics. Google launched GA4 in October 2020 and made it the only supported version on July 1, 2023.

Is GA4 free?

Yes, GA4 is free for businesses of any size. A paid enterprise version called GA4 360 adds higher data limits, longer retention (up to 50 months), service-level agreements, and faster data freshness. Most companies stay on the free version indefinitely.

How is GA4 different from Universal Analytics?

GA4 uses an event-based data model, tracks websites and apps in the same property, and applies data-driven attribution by default. Universal Analytics used a session-and-pageview model, tracked web only, and defaulted to last non-direct click attribution. Reports, metrics, and even the definition of a session changed in GA4.

Does GA4 still use UTM parameters?

Yes, GA4 reads utm_source, utm_medium, utm_campaign, utm_term, and utm_content from URLs and exposes them in the Acquisition reports. GA4 also supports four additional parameters: utm_id, utm_source_platform, utm_creative_format, and utm_marketing_tactic.

Can GA4 import historical Universal Analytics data?

No. Universal Analytics data cannot be migrated into GA4 because the data models are incompatible. Teams that need historical comparisons must export UA data to BigQuery, a spreadsheet, or a data warehouse before the UA interface is fully removed.

To make sure your campaigns appear correctly in GA4, validate every tagged link first with the GA4 URL tester at linkutm.

Back to Glossary