# What Is Retargeting? How It Works and the Rules

> Retargeting shows ads to people who have already interacted with your business. This guide explains how it works, why it can be effective, the UK consent rules, and how to use it without annoying people.

*Section: Marketing — By Harper Quinn (Marketing & Growth Editor) — Published January 17, 2025 — 5 min read*

Canonical URL: https://dailyjunction.org/marketing/what-is-retargeting
Tags: retargeting, remarketing, digital advertising, cookies, PECR

## Key takeaways

- Retargeting (or remarketing) shows ads specifically to people who have already visited your site or engaged with your business.
- It works by tagging visitors — historically with cookies — and then showing them relevant ads as they browse elsewhere.
- It can be effective because it reaches warm prospects who already know you, often at a lower cost per result.
- In the UK, the tracking that powers retargeting generally needs consent under PECR and the UK GDPR, enforced by the ICO.
- Used badly it feels intrusive; cap the frequency, set sensible time limits and exclude people who have already converted.

You browse a pair of shoes, decide to think about it, and for the next week those exact shoes seem to follow you across the internet. That is retargeting — and while it can feel a little uncanny, there is a straightforward logic behind it. Most people who visit a website leave without buying. Retargeting is the attempt to win some of them back by advertising specifically to people who have already shown interest, rather than starting cold with strangers. Done well it is one of the more efficient forms of online advertising; done badly it is the reason people reach for an ad blocker.

*This article is general information about marketing practice and UK rules, not legal advice. For anything specific to your business, check the ICO's guidance or take professional advice.*

## What it is

**Retargeting, also known as remarketing, is online advertising aimed specifically at people who have already interacted with your business** — most commonly by visiting your website. Instead of paying to reach a broad, cold audience, you concentrate your advertising on "warm" prospects who already know you exist and have shown a flicker of interest.

The premise is simple and well founded: a person who has visited your site, viewed a product or started a checkout is far more likely to buy than someone who has never heard of you. Retargeting reaches that person again at the moment they are most persuadable. It tends to do its best work lower down the [marketing funnel](/marketing/what-is-a-conversion-pixel), nudging interested people towards a decision rather than creating awareness from scratch.

## How it works

The mechanics are less mysterious than the experience suggests. In the classic version:

1. A visitor arrives at your website.
2. A small piece of tracking code tags their device — historically using a **cookie**, a tiny file stored in the browser.
3. As that person browses other websites and apps that carry advertising, the ad platform recognises the tag.
4. It shows them your ads, reminding them of what they looked at and encouraging them back.

Cookies have long been the workhorse here, though the industry is shifting as browsers restrict third-party tracking. Today retargeting also draws on other signals, depending on the platform:

| Retargeting based on | Example audience |
|----------------------|------------------|
| Website visits | Everyone who viewed a product page but did not buy |
| Specific actions | People who added to basket and abandoned it |
| Customer lists | Uploaded email addresses of existing contacts |
| Engagement | People who watched a video or interacted with a social post |

The common thread is that every audience is built from people who have already done something, which is what separates retargeting from ordinary advertising to strangers.

## Why it can be effective

Retargeting earns its place for a few practical reasons:

- **It reaches warm prospects.** Familiarity does a lot of the persuasion work, so these audiences often convert at a higher rate than cold ones.
- **It is efficient.** Because you are advertising to a smaller, more interested group, the cost per result is frequently lower, which helps the wider job of [measuring marketing ROI](/marketing/measure-marketing-roi).
- **It recovers near-misses.** Abandoned baskets and half-finished enquiries are some of the most valuable audiences of all — these people were moments from converting.
- **It keeps you in mind.** For considered purchases that take time, a gentle reminder during the decision period can be the difference between being chosen and being forgotten.

None of this makes retargeting magic. It works best as one part of a broader plan, reinforcing other activity rather than carrying the whole campaign.

## The UK rules: consent and tracking

Here is the part businesses most often overlook. Retargeting itself is lawful, but the *tracking* that powers it is regulated, and getting this wrong is a real risk.

In the UK, two overlapping frameworks apply, both overseen by the **Information Commissioner's Office (ICO)**:

- **PECR** (the Privacy and Electronic Communications Regulations) generally requires **consent before placing non-essential cookies** or similar tracking technologies on someone's device. Retargeting cookies are non-essential, so they fall squarely within this.
- **The UK GDPR** governs the personal data involved in identifying and profiling people for ads.

In practice this means you need a proper **cookie consent mechanism** — a banner that lets people genuinely accept or reject non-essential cookies, not a pre-ticked box or a wall that only offers "accept" — and clear, honest privacy information explaining what tracking you use and why. The ASA's rules on honest, clearly identifiable advertising also apply to the ads themselves. Treat compliance as the price of entry, and lean on the ICO's own cookie guidance for the detail.

## Using retargeting without annoying people

The line between a helpful reminder and an unwelcome stalker is thin, and crossing it does real damage to your brand. A few habits keep you on the right side:

- **Cap the frequency.** Limit how many times a person sees your ads in a given period. Endless repetition breeds irritation, not sales.
- **Set sensible time limits.** Someone who looked at a product three months ago has probably moved on. Stop retargeting after a window that suits your buying cycle.
- **Exclude people who have converted.** There is nothing more irritating — or more wasteful — than being shown ads for something you have already bought. Remove customers from the audience promptly.
- **Keep the ad relevant and fresh.** Show people something useful, and rotate creative so the same image is not following them for weeks.
- **Respect the opt-out.** People who declined tracking should not be retargeted. Honouring that is both the law and basic good manners.

Get this balance right and retargeting feels like a timely nudge. Get it wrong and it becomes the textbook example of advertising that makes people dislike a brand.

## The bottom line

Retargeting shows ads to people who have already interacted with your business, reaching warm prospects who are more likely to buy than cold strangers. It works by tagging visitors — long via cookies, increasingly via other signals — and showing them relevant ads elsewhere online, which makes it efficient and especially good at recovering near-misses like abandoned baskets. But the tracking behind it needs genuine consent under PECR and the UK GDPR, enforced by the ICO, so a proper cookie banner is essential. Cap the frequency, set time limits and exclude existing customers, and retargeting becomes a smart, well-mannered way to turn interest into sales rather than an exercise in following people around the web.

## Frequently asked questions

### What is retargeting?

Retargeting, also called remarketing, is a form of online advertising that shows ads to people who have already interacted with your business — typically by visiting your website. Instead of advertising to strangers, you reach people who have shown some interest, reminding them of your product or service as they browse elsewhere online.

### How does retargeting work?

When someone visits your website, a small piece of tracking code tags their device — historically using a cookie. Advertising platforms can then recognise that person on other sites and apps and show them your ads. You can also retarget based on other signals, such as people on an email list or those who watched a video, depending on the platform.

### Is retargeting legal in the UK?

Retargeting is legal, but the tracking that powers it is regulated. Under PECR you generally need consent before placing non-essential cookies or similar technologies, and the UK GDPR governs the personal data involved. In practice this means a compliant cookie consent banner and honest privacy information. The ICO enforces these rules.

### Why do I keep seeing ads for something I looked at?

That is retargeting in action. Because you visited a site or viewed a product, you were tagged as an interested visitor, and the business is now showing you ads across other sites to encourage you back. Well-run campaigns limit how often this happens and stop after a sensible period; poorly run ones can feel like being followed.

## Sources

- [Information Commissioner's Office (ICO)](https://ico.org.uk/)
- [Advertising Standards Authority (ASA)](https://www.asa.org.uk/)

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