How Google Analytics 4 Works

Google Analytics 4 (GA4) is a powerful, event-driven analytics tool that enables users to collect, analyze, and understand data from their website or app. It fundamentally works by tracking user interactions, or 'events', on your site or app, providing insights into user behavior, and facilitating data-driven decision making. Its cross-platform functionality allows it to track user journeys across different devices and platforms, providing a holistic view of the customer experience. GA4 leverages Google's machine learning capabilities to detect data trends and offers predictive metrics, enhancing the precision of forecasting and strategy planning. Furthermore, it's designed with privacy and data regulations in mind, offering robust privacy controls and the ability to work in a cookie-less future. GA4 also integrates seamlessly with Google BigQuery, enabling users to run complex queries against their analytics data for deeper analysis. In essence, GA4 provides a more detailed, flexible, and future-proof analytics solution.

When a visitor accesses a page on your site, a request is made to the webserver to display the page.
The page is served and the Google Analytics Tracking Code JavaScript is executed. The Google Analytics Tracking Code, which is a snippet of code that you place on each page of your site, calls the trackPageView() method.
At this point, the Google Analytics first-party cookies are read and/or written.
The webpage then sends an invisible gif request containing all the data to the secure Google Analytics reporting server, where the data is captured and processed. Data is processed regularly throughout the day and you can see the results in your reports.

Google Analytics uses only first-party cookies, which are considered safe and non-intrusive by most internet users today. Although many people block third-party cookies from being set by their web browsers, this will not affect Google Analytics.
Someone who blocks all cookies, however, will not be tracked by Google Analytics since all the data is passed to the Google Analytics servers via the first-party cookies. Someone who deletes their cookies will still be tracked, but they will be identified as a new visitor to the site and Google Analytics will not be able to attribute their conversions to a prior referring campaign.
People delete cookies for many reasons, one of which is to prevent personal data from being captured or reported. But, note that Google Analytics does not report on personally identifiable information. You will learn more about cookies as they relate to Google Analytics in a later module. A much less common scenario is that a visitor to your site has disabled JavaScript on his or her browser. A visitor who disables JavaScript will not be tracked since the Google Analytics Tracking Code cannot be executed.
Cached pages are saved on a visitor's local machine and so they are not served by the webserver. Google Analytics will still track visits to cached pages as long as the visitor is connected to the internet. JavaScript errors occur when an element of a web page's script contains an error or fails to execute correctly. If an error occurs before the Google Analytics Tracking Code is executed, the visit to the page will not be tracked.
In general, no reporting tool can ever be 100% accurate. You will get the most out of web analytics if you focus on trends. Knowing that 20% or more visitors converted following a marketing campaign is more powerful than knowing that exactly 10 people visited your site today.

All data collected by Google Analytics is anonymous, including where visitors comes from, how the visitors navigate through the site, and other actions they may perform. No personally identifiable information is collected. Google does not share Analytics data with any 3rd parties. Furthermore, Google optimization, support, and sales staff may only access a client's data with the client's permission. You may elect to share your Google Analytics data "with other Google products", and Google will use the data to improve the products and services we provide you. Electing to share your data "Anonymously with Google and others" allows you to receive a benchmarking report. To provide benchmarking, Google removes all identifiable information about your website, then combines the data with hundreds of other anonymous sites in comparable industries and reports them in an aggregate form.
If you select "do not share my Google Analytics data", you will not receive a benchmarking report and may not have access to specific ads-related features such as Conversion Optimizer. Again, regardless of your Data Sharing settings, Google does not share Analytics data with any 3rd parties.