Tracking basics

Website tracking basics, in plain English

If the jargon around website tracking makes your eyes glaze over, start here. These are the foundations, what each tool and term actually means, written for business owners and marketers, not engineers. Understand these and the rest of the guides make sense.

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21 guides in this topic

Every tracking basics guide

Browse all 21. Each one is a single, specific answer, in plain English.

What is a conversion?

A conversion is simply any action on your site that you have decided counts as a success.

What is a data layer?

A data layer is a structured bundle of information about the page and the user that your tags can read from, in one consistent place, rather than each tag trying to scrape it off the page.

What is a tracking pixel?

A tracking pixel is a tiny piece of code, historically a 1x1 invisible image, that loads when someone visits a page or takes an action, telling a platform like Google or Meta that it happened.

What is a UTM?

A UTM is a small piece of text you add to the end of a link so your analytics can tell exactly where a click came from.

What is conversion tracking?

Conversion tracking is the system that tells your ad platforms which clicks actually led to something valuable, a sale, a lead, a booking, so they can optimise toward the right outcome.

What is event tracking?

Event tracking is measuring specific actions people take on your site, a click, a form submit, a video play, rather than just which pages they viewed.

What is GA4?

GA4, or Google Analytics 4, is Google's current free analytics tool.

What is Google Analytics?

Google Analytics is Google's free website analytics tool.

What is Google Tag Manager (GTM) and how does it work?

Google Tag Manager explained in plain English: what tags, triggers, variables and the dataLayer are, why GTM exists, and the mistakes that quietly break tracking.

What is retargeting?

Retargeting, also called remarketing, is advertising to people who have already visited your website or app.

What is server-side tracking, and do you actually need it?

Server-side tracking in plain English: what it is, how it differs from browser tracking, what it fixes (iOS, ad-blockers, consent) and an honest view of when it’s worth it.

What is the Meta (Facebook) Pixel?

The Meta pixel is Facebook and Instagram's tracking tag.

What is a GCLID?

A GCLID is the click ID Google Ads adds to your links so conversions can be matched back to the ad. Here is what it is, how auto-tagging sets it, and what breaks it.

What is marketing attribution?

Marketing attribution decides which channels get credit for a sale. Here is what attribution means, the main models, and why no single model is the 'true' answer.

What is an attribution (lookback) window?

An attribution window is how far back a platform looks to credit an ad for a conversion. Here is what it means, why 1-day and 7-day windows give different numbers, and how to set it.

What is a view-through conversion?

A view-through conversion credits an ad someone saw but didn't click. Here is what it means, why it inflates platform numbers, and how to treat it in reporting.

What is first-party data (and why it matters now)?

First-party data is information you collect directly from your own audience. Here is what it is, how it differs from third-party data, and why it is the future of tracking.

What is the Google tag (gtag.js)?

The Google tag is the single snippet that connects your site to GA4 and Google Ads. Here is what gtag.js does, how it differs from GTM, and which you should use.

What is engagement rate in GA4 (and where bounce rate went)?

GA4 leads with engagement rate instead of bounce rate, and the two are mirror images. Here is what engagement rate measures and how to read it without being misled.

What is cross-domain tracking?

Cross-domain tracking keeps one visitor as one journey when they move between two of your domains. Here is what it is, when you need it, and how it differs from subdomains.

What is conversion rate, and how is it measured?

Conversion rate sounds simple but GA4 can measure it several ways. Here is what conversion rate means, the difference between session and user rates, and how tracking skews it.