What Is Ad Tracking?

Ever wondered why ads on websites often look a little too personalized? That’s because companies use tracking software and other methods to better understand your online habits and target you with personalized ads. Learn what ad tracking is, how internet ads are tailored to you, and how a secure browser can help you stop online ad tracking.

Written by Domenic Molinaro
Published on December 18, 2020
Reviewed by Antoinette Cocorinos

What is online ad tracking?

Ad tracking happens when companies use cookies and other tracking methods to follow you online and gather insights into your behavior and preferences to serve you more relevant, targeted ads. Ultimately, the purpose of ad tracking is to help websites and companies offer you more personalized goods and services and thus sell you more stuff.

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    There are, of course, many reasons websites and other actors track you around the web — it’s not just to entice you to open up your wallet (or bug you). But what are ad trackers, exactly?

    Common ad tracking techniques

    There are many types of ad trackers: cookies, URL trackers, tracking pixels, and more advanced techniques that use special scripts, like browser fingerprinting. Each of these methods gathers and logs your data a bit differently. But they all help companies build an advertising profile of you by essentially spying on your browsing habits.

    Websites and apps use specialized code that logs your activity in your browser, and this is how both the sites themselves as well as third parties can figure out who you are and what you want or need. Armed with this data, they then try and sell you more relevant products and services. That’s how companies track you online and why you so often see those seemingly magical ads that keep following you around the internet.

    Here are some of the most common ad tracking methods that websites use.


    Companies place cookies — little pieces of code that record your online activity and save it in your browser — all across the web to identify you as you hop from one site to the next, adding increasingly rich data to your advertising profile. Cookies are the most common source of ad tracking, and many sites use the same third-party cookies. We’ll explore this in more depth later on.

    URL trackers

    Tracking URLs are links with little strings of code on the end that track your behavior after you click on them. They’re like cookies, but rather than hiding in scripts, they’re out in the open, running along your browser’s address bar. If you visit a site after clicking on a tracking URL, all your activity on that site can be logged and collected by whoever originally set up the URL.

    Here’s an example of what a typical website URL may look like: www.website.com/some-page

    But, if you came to the site by clicking on a newsletter in your email, the URL may actually look like this: www.website.com/some-page/?utm_campaign=newsletter-campaign&utm_source=email

    All the extra information appended to the end of the URL lets the site’s administrators know that you arrived from a campaign newsletter sent to your email.

    Tracking pixels

    Tracking pixels are tiny dots (1 x 1 pixels) stuck onto emails and websites that can detect whether a certain piece of content was accessed and how it was interacted with. Rather than being saved in your browser, pixel data is sent directly to a company’s server. Pixels can help identify your IP address, see if you’ve opened an email, log any attachments you’ve downloaded, and more. Without the aid of certain browser extensions, you also can’t block them (currently), like you can with cookies. Pixels are like invisible, unblockable cookies.

    Why companies track you

    Advertising is the main source of revenue for big tech, and in the case of Facebook, advertising makes up almost all of their income. Websites and apps let huge platforms — along with tons of other advertising companies — install ad trackers because then those platforms can advertise the same websites and apps more effectively. More data, more money. And though ad tracking mostly benefits those watching you, there are certainly benefits to being tracked as well.

    Benefits of ad tracking

    Relevance. By tracking you, advertisers can serve you ads based on your geographical location and viewing habits, which is helpful if you’re looking for weather conditions where you live or the game time of your local team. Ad tracking can inform you about a product you might actually want to buy, sales offers near you, and products you never would have known about otherwise. If you have to deal with ads anyways, they might as well be relevant and, perhaps, interesting.

    Convenience. Ad tracking helps app developers maintain and improve their products, making them easier for you to use. For example, Google can make routes on their maps more accurate — and provide updated traffic conditions — by tracking people through their GPS.

    Drawbacks of ad tracking

    Privacy invasion. It’s your data, isn’t it? What gives companies the right to spy on you? Though you might not mind companies seeing what products you view, it’s a different story when they start examining your medical history or probing your dating life.

    Loss of time. By being shown more “relevant” ads more often, you keep scrolling, clicking, and browsing longer. Most of us are already a bit uncomfortable with how much time we spend in front of screens, especially when on social media or other addictive apps. No matter your age, average screen time is on the rise. Ad tracking exacerbates this issue. 

    Loss of money. In addition to being a time drain, ad trackers steer you toward products that drain your wallet. If it’s something genuinely useful, that’s fine, but often people end up buying things they don’t really need, based purely on impulse. Self-control only goes so far.

    It’s weird. Let’s face it, no one likes being watched without their consent. It strikes many people as just fundamentally wrong. And with technology having become an integral part of people’s lives, ad tracking can make it feel like someone is constantly watching you.

    Ad tracking technology lets companies collect all kinds of different data and use that to develop customer personas.Ad tracking technology can make it seem like someone is always watching and tracking everything you do online.

    How companies track you online

    Ad tracking works by compiling a profile of you based on actions you take online — whether clicking on something, filling out a form, scrolling, or adding something to your shopping cart. Those actions are logged by individual ad trackers and stay logged (in your browser or on a server) so that they can be accessed and stitched together later, usually by a powerful AI (artificial intelligence) that can often predict your behavior better than you can.

    Say you’re looking up flights to an exotic location, and the site you use has a Google ad tracker installed (which is likely). Then, later that week, you start checking out engagement rings at local jewelers, and you use Google maps to get to some of them. During the same week, you also search YouTube, owned by Google, for “romantic ways to pop the question.” 

    Suddenly, you start seeing ads for stationery, bakeries, and caterers near you. These companies have paid Google to target ads to people in your area who they think might be getting married soon.

    Can cookies track you?

    By themselves, cookies can’t track you. But by collecting data from hundreds or thousands of cookies, the company who owns them or sets them up can get a very good idea of what to sell you.

    Some cookies are required for websites to work properly. But companies love to say that they use cookies to better understand their visitors or to make their websites run more smoothly — without mentioning tracking cookies and advertising. Cookies and advertising are like the proverbial good cop/bad cop trying to trick you into handing over the information they want.

    But what was the original purpose or function of cookies, and how did that change? And how do cookies work for advertising? 

    As you navigate the web, click from site to site, and enter info here and there, websites need to remember who you are and what you do — your login information, language preferences, settings, and so on. If not, you would just appear as a brand-new visitor each time the page refreshes.

    Cookies allow websites to remember which items are in your shopping cart when you click through to the shipping and payment screen. Websites can’t simply store all their visitors’ information on their servers, because that would take too much space and cost too much. 

    Cookies solve that problem. By storing your information in a cookie and sending it back to your browser, a server lets the browser verify you from that point on. These kinds of cookies are known as first-party cookies. When companies discovered they could use this technique to gather consumer data, they created third-party cookies, which is just a generic name for advertising cookies.

    A browser can verify a user with information that a server sends to a cookie.Cookies help websites identify their visitors and create customized pages or experiences.

    Third-party cookies save all sorts of information, not just functional data. A Facebook “like” button on another website, for example, is a third-party cookie that can tell Facebook’s server that you visited and what you did there. Later, when you go to another site that also has a Facebook button, Facebook can gather even more information to add to your profile. 

    You can disable cookies, or even delete them entirely, but that’s often just the first step. While it feels nice to press that “clear cookies” button, everything you did before you pressed it is still saved on a powerful computer somewhere. Some innovative companies have figured out that a better approach to anti-tracking is to add fake data to the equation to create a cloudier picture.

    Beyond cookies, some websites can detect your device’s unique “fingerprint” by using hidden scripts to analyze your precise hardware, software, and settings. With enough digital attributes — your operating system, browser settings, time zone, language, screen resolution and color depth, audio and video capabilities, and more — companies can identify you out of a crowd and perform ad tracking without any cookies at all.

    Avast’s anti-tracking software masks your digital fingerprint and inserts fake data into trackers to put them off your trail. Plus, we'll clear your cookies automatically to keep you anonymous. Whether it’s a random analytics company or a huge conglomerate trying to record your behavior, Avast AntiTrack’s comprehensive browser protection will stop them dead in their tracks.

    What do advertisers do with my data?

    Advertisers collect your data so that they can target you when other companies pay them to do so. Facebook and other advertisers offer what’s called retargeting services, which means they track products you came close to buying but left in your shopping cart instead. Later, when you see an ad for the same product or a similar one, that means you’re being retargeted

    Your data can also be plugged into artificial intelligence systems to improve their models so they can be used to track and advertise more effectively. They use fancy terms like “analytics,” “propensity modeling,” and “predictive marketing,” but it’s usually just a way to try to figure out how to market and sell more effectively.

    Websites and app developers allow ad trackers because effective advertising means more traffic, user data, and revenue. And it’s not just huge companies that use ad trackers. All sorts of companies collect your data for various reasons — data brokers even buy and sell it. Here’s a primer on how Google uses your data, for example.

    Is ad tracking illegal?

    Ad tracking is a legal gray area. For a long time, there were no regulations around ad tracking, but when people started realizing what was being done with their personal data they began to worry. 

    The European Union’s GDPR, or General Data Protection Regulation, attempts to protect citizens and consumers. The GDPR requires user consent before websites can collect personal data — such as names, dates of birth, email addresses, photos, location data, and so on. It also requires consent before companies can log info relating to your physical, physiological, genetic, mental, economic, cultural, or social identity. You may have noticed a lot more pop-ups lately asking you to agree to third-party cookies. That’s GDPR in practice.

    The problem is that these pop-ups are disruptive (and annoying) — so most people don’t read them and companies use so-called dark patterns to make it hard to opt out. Also, with the massive amount of data being processed, it’s hard for regulators to determine legal compliance. You may have also heard about “the right to be forgotten” in the EU, which stipulates that if you ask companies to delete your data they have to comply. But this right is not absolute, and companies will find loopholes wherever they can.

    In the US, the California Consumer Protection Act (CCPA) that went into effect in January 2020 also lets you request that your data be deleted, and it requires companies to inform consumers about data breaches. The major difference between the GDPR and the CCPA is that the latter only determines the right to opt-out — it doesn’t require consent before companies can track you. Instead, you have to specifically request or find a way to opt-out, or else your data can be collected by default.

    Can you see who’s tracking you online?

    It’s not really possible to see every single company that has access to your data. Some estimates suggest that over 75 percent of all websites are tracking you, with loads of trackers on each one. Google lets you download your data, and Facebook has recently let you download your data as well, but you can’t see who they’re doing business with to target you. 

    One of the best strategies against tracking cookies is to confuse them. Along with clearing ad trackers off your browser, good anti-tracking software adds fake data to your browser so that the companies tracking you can’t get an accurate picture. 

    Sometimes it’s best to use someone’s own tactics against them, and masking your identity with fake information is one of the best ways to keep your private information safe. Along with obscuring your real identity, Avast AntiTrack will clean up your cookie trail and reveal the companies trying to track you.

    How to stop ad tracking

    If you’re wondering how to stop retargeting ads or block ad tracking completely, the best way is to use a dedicated tool, whether it be anti-tracking software or a secure browser built specifically for enhanced privacy and security. 

    And while VPNs can help hide your location, they won’t warn you about tracking attempts, obscure your device fingerprint, or clear your cookies. Some people think that using incognito mode prevents them from being spied on, but it only goes so far. Using private browsing (often referred to as going incognito) can help block ad tracking to an extent, but it only clears your cookies at the end of the private browsing session. Private browsing can’t block IP address tracking, browser fingerprinting, or other tracking methods.

    You can add ad blocker extensions to your desktop, Android ad blockers, or apps to prevent ads and tracking on your iPhone to see fewer annoying ads, but these blockers don't prevent advertisers from tracking you. Avast Secure Browser is one of the best ways to combat tracking, because it defends your data on multiple fronts.

    Protect yourself from ad tracking the easy way

    The best way to avoid online ad tracking is to not be detected in the first place. By protecting your identity and browsing behavior on all fronts, Avast Secure Browser is your first line of defense. It finds and blocks tracking cookies automatically, along with securing your webcam, preventing hacking attempts, and encrypting your connection.

    Avast Secure Browser lets you block ads, tracking, hackers, and so much more.

    As the techniques companies use to watch you, track you, and collect your data become more sophisticated and pervasive, you need an equally sophisticated response. Browse with peace of mind, knowing that Avast Secure Browser is shielding you from any prying eyes.

    Block online ads and prevent web tracking with Avast Secure Browser for iOS

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    Domenic Molinaro