How to check in two minutes
Open the site, press Ctrl+U and search for “UA-”. Then search for “G-” and “GTM-”. If only UA- appears, you have the old code. If G- or GTM- appears, you have GA4 or Tag Manager; you still need to check in your Google account that the data is actually arriving.
GA4 is not UA under another name
GA4 measures events, not “page visits”. That is useful for a business: you can see how many people tapped your phone number, how many opened WhatsApp and how many submitted the form. These are exactly the actions that bring in customers, not the visits themselves.
Why use Tag Manager
With Tag Manager you place a single code on the site and manage the rest from Google's interface: GA4, the Facebook pixel, Google Ads conversions. When you want to add a new event, you no longer have to change the site. Tag Manager is not analytics in itself: without GA4 configured inside it, it measures nothing.
Cookie consent
GA4 and the Facebook pixel set cookies, so you need a consent banner and, done properly, Consent Mode v2, which starts measurement only after the visitor accepts. Without it you risk a complaint, and your data is incomplete anyway.
Which events are worth tracking for a small business
Phone clicks, WhatsApp clicks, contact form submissions, email clicks and views of the contact page. Five events are enough to know where your enquiries come from: organic Google, Ads, Facebook or referrals.