Pixels and cookies are popular marketing and advertising tools that can give you a clearer picture of your customer base and their preferences.
Although they’re widely used, it’s easy to confuse them for one another. But as a marketer, you need to know how tracking pixels and cookies work, and how they differ. That way, you can effectively implement these tracking technologies to help you understand your users while staying compliant with data privacy laws.
Below, we unpack how pixels and cookies work and explore their different purposes and uses. Plus, you’ll see how Usercentrics can help your business achieve and maintain privacy compliance while gathering meaningful marketing insights.
Key takeaways
- Tracking pixels and cookies both collect user data, but pixels store information on external servers while cookies store it locally in the user’s browser.
- Pixels power ad tracking and cross-device insights, while cookies primarily support personalization, analytics, and on-site functionality.
- Both technologies are only privacy-compliant when users are properly informed about their use and have meaningful control over how their data is collected and used.
- Under many privacy laws, like the GDPR, non-essential cookies and pixels cannot be used until users give explicit consent for their use via a clear opt-in mechanism.
- Using a consent management platform (CMP) like Usercentrics’ helps businesses automate tracker blocking and manage consent records to achieve and maintain privacy compliance.
What are tracking pixels and cookies?
Both cookies and pixels help website owners, marketers, and advertisers collect data about user activity. While they are very similar technologies, there are key differences in how they work and what purposes they serve.
What is a tracking pixel?
A pixel, which might also be called a marketing pixel, storage pixel, or pixel tag, is a 1×1 pixel image that’s embedded in web pages, emails, and digital ads.
This tiny piece of code works quietly in the background of your digital property and records valuable insights about user activity. When a user loads a web page, opens an email, or clicks on an ad, the pixel triggers a web server request to record data about that visitor’s behavior.
Tracking pixels can help you understand user behavior and track campaign performance across different websites and digital assets. That data reveals how users interact with your content, which ads they’ve seen, and what actions they’ve taken afterward, like clicking a link or completing a purchase.
Websites typically use three categories of pixels:
- Engagement pixels, which monitor how users interact with a web page or campaign element, e.g., time on page and clicks.
- Retargeting pixels, which track users who’ve already visited a site so marketers can serve them relevant ads elsewhere online.
- Conversion and custom event pixels, which capture when a specific action occurs, like signing up for a newsletter or completing a checkout.
Platforms like Meta and Google Ads rely heavily on ad tracking pixels to optimize campaign performance. For instance, if you have the Meta pixel embedded on your website and someone views a product page, Meta will prioritize showing that user ads for your product on Facebook or Instagram.
What is a cookie?
Cookies are small text files that are added to a user’s browser when they visit a website. Because they enable websites to remember useful information like login details, language preferences, and shopping cart contents, they’re essential to how most websites function.
When a user visits a site, cookies are created and stored locally on the user’s device. If that person returns to the website later, those browser cookies enable the website to personalize their experience or remember past actions.
Tracking cookies can also be used to monitor user behavior across sessions or even different websites, which helps advertisers deliver more relevant content or measure campaign results.
There are two main types of cookies: first-party and third-party cookies. First-party cookies are created and stored by a website the user is visiting. They typically support functionality and are generally considered non-invasive.
Third-party cookies, on the other hand, are placed by external service providers, such as ad networks or data aggregators, to track users across multiple sites for advertising or analytics purposes.
Each of these different types of cookies can also be categorized as either session or persistent cookies. Session cookies are temporary, and are deleted when a user closes their browser. Persistent cookies remain on a user’s device for a set period to help sites recognize returning visitors over time.
Without cookies, the personalized experiences and targeted marketing strategies that modern marketers have come to rely on wouldn’t be possible.
How do pixels and cookies work, and what are the differences?
Cookies and pixels both collect data when a user lands on a web page, and both help marketers understand behavior and measure engagement. However, there are key differences between how these technologies function and how visible they are to users.
Cookies store information in the browser on a single device and are sent back to the server with each request. A tracking pixel, on the other hand, sends information to a server when a web page or email is loaded, which enables cross-site tracking.
The former are generally more visible to website visitors, as they often require cookie consent and can be controlled by a user through their browser settings. The use of pixels, in contrast, is harder for users to block. Doing so often requires them to use ad blockers or disable automatic image loading.
Take a look at the table below for an overview of the main differences between pixels and cookies.
| Functionality | Cookie | Pixel |
| Storage | In the user’s browser | On an external web server |
| Awareness and control method | Can be accepted or denied by the user via a cookie consent banner and can be managed or blocked in browser settings | Only disclosed in a website privacy policy and more difficult for users to block |
| Main use case | Personalization, analytics, retargeting | Ad tracking, conversions, cross-device insights |
| Compliance requirements | Requires clear notice and explicit consent according to most privacy laws | Requires clear notice and explicit consent according to most privacy laws |
Data privacy compliance implications for pixels and cookies
Neither cookies nor pixels are inherently compliant or noncompliant with privacy laws. What matters is whether website owners obtain valid consent before they collect data to give users genuine control over their information.
Under privacy laws like the European Union’s General Data Protection Regulation (GDPR), Brazil’s General Data Protection Law (LGPD), and South Africa’s Protection of Personal Information Act (POPIA), organizations must get explicit consent before activating tracking technologies that aren’t strictly necessary for website operations. These frameworks follow an opt-in model, which means users must actively agree before data can be processed.
Some laws follow an opt-out model, like the California Consumer Privacy Act (CCPA) and other US state-level privacy laws. Opt-out models permit tracking to occur by default, unless a user opts out, and these laws require website owners to offer users an easy way to do so.
Whether a user simply visits a website or engages with an ad, compliance controls help protect user privacy by helping individuals understand how their information is used. That way they can decide for themselves whether they want to share their data.
Offering transparency surrounding data collection practices and providing users with granular consent controls reduces regulatory risk and helps to build trust with your audience.
Are tracking cookies illegal?
Tracking cookies aren’t inherently illegal, you need to use them in a way that complies with the requirements of privacy laws and other frameworks.
Cookies that are used purely for essential functions are typically exempt from consent requirements. Essential functions could include storing login information or remembering what items a user has put in their shopping cart.
Those that collect data for analytics, advertising, or profiling are considered non-essential and require clear, valid consent before they can be activated under many privacy laws.
When a user visits a website, a cookie consent banner should appear to request permission before any tracking cookies are activated. If the user agrees, the cookies can be deployed and proceed to store data.
Is pixel tracking illegal?
Pixel tracking is legal, but it introduces privacy compliance risks because pixels are typically invisible to users.
When a tracking pixel loads, it sends a request to a web server, which records information such as page views, clicks, and conversions for ad campaigns and other purposes. Because pixels collect and share personal data, they must meet many of the same data privacy requirements as cookies.
Under the GDPR and other opt-in data privacy laws, these pixels must remain blocked until the user has given valid consent. This becomes even more important given that this information is frequently transmitted to third parties like Meta or Google.
In the U.S., many state-wide regulations also classify pixels as data-sharing technologies. That means you must provide users with a clear way to opt out of having their data shared for personalized ads or profiling.
Best practices for compliant pixel, cookie, and tracker use
To use pixels and cookies responsibly, you need to be transparent about how you collect data and give users control over their preferences. Here are a few best practices to follow:
- Display a consent banner: Clearly inform users about what data you collect and why, and who may have access to the data.
- Automate tracker blocking until consent is given: Prevent any non-essential pixels or cookies from firing before you obtain consent.
- Offer accessible, granular user control: Provide clear mechanisms for users to adjust or withdraw their consent preferences at any time.
- Maintain consent records: Keep detailed logs showing when and how users granted, withdrew, or modified consent for auditing and accountability.
These steps can help businesses responsibly and compliantly track users for cross-context behavioral advertising and more.
Effectively manage cookies and tracking pixels for privacy-compliant operations and increased customer trust
Managing cookies and tracking pixels responsibly will help you stay compliant with data privacy laws and maintain user trust.
The Usercentrics Consent Management Platform (CMP) makes it simple to use these technologies to collect data in a way that aligns with global privacy frameworks. The CMP automatically blocks trackers until valid consent is given, and it logs and stores every consent interaction as an audit-ready record.
What’s more, you can analyze user behavior and interactions and A/B test banner options to maximize opt-in rates and get the insights that help you exceed your marketing goals.
Usercentrics can help your business operate confidently across jurisdictions while maintaining transparent data practices that strengthen privacy compliance without compromising on marketing performance.
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