{"id":63016,"date":"2019-10-22T00:00:00","date_gmt":"2019-10-22T00:00:00","guid":{"rendered":"http:\/\/blog.mozilla.org\/foxtail\/2019\/10\/22\/what-is-a-web-tracker\/"},"modified":"2021-02-09T01:46:26","modified_gmt":"2021-02-09T01:46:26","slug":"what-is-a-web-tracker","status":"publish","type":"post","link":"https:\/\/blog.mozilla.org\/en\/uncategorized\/what-is-a-web-tracker\/","title":{"rendered":"What is a web tracker?"},"content":{"rendered":"

Let\u2019s say you\u2019re on an outdoor pizza oven website dreaming about someday owning one. Mmm pizza. Next you switch gears and visit a fitness site; lo and behold an ad for the pizza oven you were just looking at is there, too. Then you go to YouTube to see how easy it would be to build your own pizza oven (it\u2019s too hard), but first you have to sit through an advertisement about, you guessed it, that same pizza oven. Time to check Instagram on your phone, and there it is again, grinning at you as a sponsored post in your feed.<\/p>\n

It\u2019s not just a feeling. That ad really is following you and it happens all the time. So how do these sites all know exactly how to tempt you to a point of annoyance? Is it magic? Nope. The answer is web trackers.<\/p>\n

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What exactly is a web tracker?<\/h2>\n

Generally, a tracker is a script on websites designed to derive data points about your preferences and who you are as you interact with their site. Sometimes these scripts are placed purposefully by the website you\u2019re on, other times a script may be from a website you\u2019ve never visited. Understanding the ways your data is collected can help you limit your exposure to trackers in the future.<\/p>\n

Types of web trackers<\/h2>\n

Cookies<\/h3>\n

These are a commonly used method to track you as you browse the web. Cookies are small pieces of data saved to your browser by websites. Every time you visit a web page, cookies can be stored on your device. But not all cookies are created equal. The website that you are visiting may have its own cookies, called first-party cookies, which are placed to suggest content that is most relevant for you, help you remember your log ins, prevent fraud, and more.\u00a0\u00a0<\/i><\/p>\n

Super cookies<\/h3>\n

A super cookie is a browser cookie that can be permanently stored on your computer. Super cookies are harder to detect and get rid of because they can’t be auto-deleted the same way as regular cookies. By injecting super cookies into your device, websites can access your personal information, behavior and preferences. Super cookies can also track the time you\u2019re most active on the internet. This next-level data is a goldmine for advertisers who can use the information to create targeted ads based on user profiling and preferences.<\/p>\n

Embedded scripts<\/h3>\n

There are a variety of tracking resources that can be embedded as visible or invisible elements on a page. Common examples are pixel trackers that are clear images embedded on a web page or email; or tracking scripts that run as you visit websites and can do a number of things to track you, from recording your IP address to capturing your device\u2019s specifications.<\/p>\n

Fingerprinters<\/h3>\n

Fingerprinting scripts<\/a> scrape data from your web browser, including your browser\u2019s type and version, your device\u2019s operating system and version, your screen resolution, installed fonts and can even see all the apps you\u2019ve downloaded on your device. This data is assembled into a fingerprint unique to your device and can be used to distinctly track you across websites.<\/p>\n