Google Analytics 4 (GA4) is Google's free tool for measuring what happens on your website or app. It replaced the old version (Universal Analytics), and Google explains the change on its official announcement page. The core difference is that GA4 is built on events: every interaction (a page view, a click, an add to cart, a purchase) is an event.

Why you need GA4 if the ad platforms already measure

Each ad platform measures its own part, and each tends to claim credit for the sale. Meta says the sale came from Meta, Google says the same about the same sale. GA4 gives you one relatively neutral picture across all sources: where visitors came from, what they did, and which source brings buyers rather than just visitors.

The five questions you need GA4 to answer

  1. Where do my visitors come from? (organic search, ads, social, direct)
  2. Which source brings sales or leads, not just visits?
  3. Where do people leave the buying journey? See the sales funnel.
  4. Does mobile behave differently from desktop?
  5. Which pages bring the most conversions?

If your reports answer these questions, you are using GA4 well, even if you never open 90% of its reports.

The basic setup

1. Installation

Through the Google tag directly, Google Tag Manager, or your store platform's integration (Shopify, WooCommerce and others).

2. The important events

GA4 records some events automatically (page views, scrolls, outbound clicks). But business events need setup: viewing a product, adding to cart, starting checkout, purchase, form submission. Google recommends specific names for these in its list of recommended events. Using them makes the built-in reports work automatically.

3. Mark key events (conversions)

Not every event matters. Mark the events that represent a business outcome (purchase, lead, sign-up) as key events.

4. Link to Google Ads

Link GA4 to your Google Ads account to see campaign data inside GA4 and import conversions. See Google Ads.

UTM parameters: do not skip them

UTM parameters are additions to a link that tell GA4 the exact source of a visit, for example:

Without them, many visits from ads, messages and email show up as "direct" or "unassigned". Give them a fixed naming scheme: the same case and format in every campaign.

For cash-on-delivery stores, UTMs are what let you tie each order to the campaign it came from, and then to its delivery status. That join is what showed, at an Egyptian store, that the cheapest campaigns were actually the most expensive. See reducing COD returns.

Reports a business owner needs

  • Traffic acquisition: sources and the conversions they drove.
  • Conversions by source: which channel brings results.
  • Pages: which pages people visit and which convert.
  • Devices: mobile against desktop.
  • Explorations: to build a custom funnel and see where the leak happens.

Common mistakes

  • Installing GA4 without setting up purchase or form events.
  • Not using UTMs in campaigns.
  • Comparing GA4 numbers to platform numbers and expecting them to match. They will not, because each tool attributes differently. What matters is the trend and large gaps.
  • Not excluding internal traffic (your own and your team's visits).
  • Recording purchases twice because the tag is duplicated.

The bottom line

GA4 is not for admiring charts, it is for answering specific questions: where customers come from, where they leave, and which channel deserves more budget. Set it up properly once, use UTMs consistently, and come back to the five questions. To have measurement in your ad accounts and GA4 reviewed together, see the freelance media buyer page.