The ad tech industry is always trying to find ways to monitor your digital activities as the more they know, the more money ends up in their pockets.

This has led to the rise of “fingerprinting”, which has security researchers worried.

Although it sounds harmless, “fingerprinting” involves looking at the many characteristics of your mobile device or computer, such as the screen resolution or operating system.

According to The New York Times, as soon as they have enough details, they can use this information to pinpoint and follow your online habits, such as how you browse the web and use applications.

Once enough device characteristics are known, the theory goes that the data can be assembled into a profile that helps identify you the way a fingerprint would.

“Get enough of those attributes together and it creates essentially a bar code,” said Peter Dolanjski, a product lead for Mozilla’s Firefox web browser, who is studying fingerprinting. “That bar code is absolutely uniquely identifiable.”

The bad news? The technique happens invisibly in the background in apps and websites, which makes it harder to combat.

As it’s a new way of discovering your web habits, the ways to protect yourself are limited as proper solutions are still in development.

However, Apple users have protections in Safari for computers and mobile devices, which makes your device look the same to a website by sharing the bare minimum of information that the site needs to load properly.

For Android and Windows users, the safety recommendation is to use the Firefox web browser, as Mozilla introduced fingerprint blocking in its browser this year. However, the feature can prevent some content from loading on certain websites.

Unfortunately, if you’re a Google Chrome user, Google hasn't announced any defence system as of yet, but it has plans to release protections in the future.

This article originally appeared on Over60.