Guide

What are website tags?

A website tag is a small piece of JavaScript that runs when someone visits a page and sends information about that visit to an outside tool, such as Google Analytics or an advertising platform. Tags are how a business knows where its visitors came from, what they did, and which marketing produced a sale.

The word “tag” is used for three unrelated things on the web, which is where most of the confusion starts. Here is the difference, followed by what tracking tags actually do and how to see the ones running on your own site.

Three different things are called tags

Search for “website tags” and the results mix all three. Only the first is what analytics and marketing people mean.

Tracking tags

also called: web tags, marketing tags, pixels

Small pieces of JavaScript that run in a visitor's browser and send data to an outside tool: Google Analytics, Google Ads, Meta, LinkedIn, a heatmap tool, a chat widget. This is what people mean by tags in analytics and marketing, and it is the subject of this page.

HTML tags

also called: elements, markup

The building blocks of a web page itself, written in angle brackets. A heading is an h1 tag, a paragraph is a p tag, an image is an img tag. They describe structure and content. They do not send data anywhere.

Content tags

also called: post tags, hashtags, labels

Keywords attached to a blog post, product or social post so it can be grouped and found. A WordPress post tagged "recipes" is this kind of tag. It is a filing label, not code.

What a tracking tag actually does

When a page loads, the browser runs the scripts on it. A tracking tag is one of those scripts. It waits for something to happen, a page loading or a button being clicked, collects a small set of details about it, and sends them to a server belonging to whichever tool it reports to.

The details are usually things like the page address, the time, a randomly generated identifier for the browser, and whatever the tag was configured to record, such as the value of an order. That request is what eventually becomes a row in a report.

Every tag on a site is therefore a third party receiving information about your visitors. That is not sinister on its own, it is how measurement works, but it is the reason tags are worth keeping track of rather than accumulating.

The main types of tracking tag

Most sites run several of these at once. They overlap, and one tool often installs more than one.

Analytics tags

Record what visitors do: pages viewed, buttons clicked, purchases completed. Google Analytics 4 is the common one. Everything in your traffic and conversion reports arrives through a tag like this.

Advertising and conversion tags

Tell an ad platform that something happened, so it can attribute a sale to a campaign and optimise bidding. Google Ads conversion tags and the Meta pixel are the usual examples. These are the tags where an error costs money directly.

Remarketing tags

Add a visitor to an audience so they can be advertised to later. Often the same script as the conversion tag, configured differently.

Behaviour and session tags

Record how people actually move through a page: scroll depth, mouse movement, session replays. Hotjar, Clarity and FullStory sit here. These carry the highest privacy sensitivity because they can capture what a visitor types.

Consent and privacy tags

The cookie banner itself, and the signals it publishes for other tags to obey. This one is different in kind: its job is to control the others rather than to collect anything.

Support and utility tags

Live chat, review widgets, A/B testing tools, personalisation scripts. Each is a third party running code on your site, and each is worth knowing about.

How tags get onto a website

There are two routes. A tag can be pasted directly into the site’s code, which means a developer has to be involved every time anything changes. Or the site can install one container script, and every other tag is added and edited inside a tag management system such as Google Tag Manager.

The second approach is now the norm, because it lets a marketing team add a tag without a code release. It also concentrates the risk: one container ends up holding everything, and if nobody reviews it, it quietly fills with tags that no longer have a purpose.

What goes wrong with tags

Tags fail quietly. Nothing on the site breaks, no error appears, and the reports keep rendering. These are the problems we see most often.

Tags that fire before consent

The banner is displayed while the tags behind it are already collecting. Under UK and EU rules the banner is meant to gate them, and it frequently does not.

The same tag installed twice

Once hardcoded in the theme, once added through a tag manager. Sessions, conversions and revenue all count double, and the reports look better than reality.

Tags nobody can account for

Scripts added for a campaign years ago, by an agency that has since moved on. Every one is page weight and a third party receiving your visitor data.

Tags that quietly stopped working

A site update changes a button or a page path, the tag that depended on it stops firing, and nothing raises an error. The number simply goes flat.

Tags carrying personal data

An email address or a phone number ending up in a URL or a tracking parameter, which breaks both privacy law and the analytics platform's own terms.

Seeing the tags on your own site

Because tags run in the visitor’s browser, they are visible to anyone who looks. The step-by-step methods are in how to find the tags on a website, and our free GTM Inspector reads any public Google Tag Manager container and lists everything inside it, with no login. If you want the setup checked rather than just listed, the website tracking audit guide covers the full process.

Website tags FAQs

What are tags on a website?

In analytics and marketing, a tag is a small piece of JavaScript that runs when someone visits a page and sends information about that visit to an outside tool, such as Google Analytics or an advertising platform. The word is also used for HTML elements and for content labels like blog post tags, which are different things entirely.

What is the difference between a website tag and an HTML tag?

An HTML tag is part of the page's own markup and describes structure: a heading, a paragraph, an image. A tracking tag is a script that sends data to a third party. HTML tags build the page. Tracking tags report on what happens in it.

Are website tags and pixels the same thing?

Effectively yes, in everyday use. Pixel is the older term, from when tracking was done with a one-by-one transparent image. Most modern tracking is JavaScript rather than an image, but the words are used interchangeably, and Meta still calls its tag a pixel.

Do website tags slow down a site?

They can. Each tag is a request to a third-party server and code executing in the visitor's browser. A handful is usually unnoticeable; containers that have accumulated dozens of tags over the years are a common cause of slow pages, which is one reason removing unused tags is worth doing.

How many tags should a website have?

There is no correct number. What matters is that every tag has an owner, a purpose and a reason to still be there. A site with six tags that are all understood is in better shape than one with thirty where nobody can say what half of them do.

Can I see what tags another website is using?

Yes, for anything published publicly. Tags run in the visitor's browser, so they are visible in the page source and in the browser's network activity. Our free GTM Inspector reads any public Google Tag Manager container and lists every tag inside it.