The internet is filled with amazing things, but it's no secret that the internet is also a huge source of revenue for some of the biggest companies in the world. One key component of why it's so profitable is targeted advertising. Targeted advertising basically means that advertisements can be shown to people who are more likely to actually engage with the advertising, as opposed to, say, a billboard on a highway where everyone sees it.
✕ Remove Ads
However, that begs the question: how do companies know what you like? Companies know a lot about you, and how they come to those conclusions ranges from the very obvious to, arguably, the downright creepy.
Companies collect data from all kinds of sources
Most pages have trackers on them
If you browse the internet and engage with certain kinds of content, chances are most of those websites are using Google's AdSense to display advertisements. Google uses a series of metrics to "fingerprint" a user, and this can be things like your IP address, specifications of your computer, and a Google account if you're logged into one. Your active browsing then informs Google's advertisements what you're most likely to be interested in, providing a profile of the kind of person that you are.
✕ Remove Ads
For example, I play a lot of Counter-Strike 2, and I have a huge interest in the game and making upgrades to my setup for FPS games. However, I have no interest in MOBAs like League of Legends. This means that an advertisement for a mouse like the Razer Naga V2 Pro with its side buttons tailored for a MOBA is very unlikely to interest me, but a new Logitech G Pro wireless mouse probably will. Google knows this about me thanks to my browsing history and the content I engage with, which makes sense. Right now, you can already see how a company would collect data like that and build a picture of what you might be interested in.
✕ Remove Ads
Yet companies don't stop there; they can go beyond your active searches and start to infer behaviors based on your physical environment. Let's say you're in a shared accommodation with someone, and that person orders DoorDash. You smell the food, and it smells good. Suddenly, you start getting DoorDash advertisements on the internet. Was your phone listening to the conversation you had with your housemate when they said they were ordering? No, instead, Google's algorithms understood that someone in your home ordered DoorDash, and it's very likely to be the case that you're starting to swing towards ordering food for yourself, too.
✕ Remove Ads
This mapping of relationships and devices is facilitated by companies like Drawbridge. Drawbridge is a people-based identity management company that matches people across devices, including people living in the same households. Companies such as Google will purchase these device maps to better inform their own advertising, which in turn means that you start to see targeted advertisements that may be meant for (or can be informed by) other people in your household. This basically combines IP targeting with inference on who you are or who you speak to, which makes it incredibly difficult to avoid and can make it seem like your devices are listening to you when they aren't.
✕ Remove Ads
As another example, let's say you have a conversation with your partner about going on vacation somewhere, and later that day you start getting advertisements for that location despite never searching it online. Was your phone listening to you then? The answer, maybe surprisingly, is still no. You didn't search it, but your partner probably did, either before the conversation or after, and Google knew that there was a relationship between your two devices and started to show those advertisements on both.
What can you do about it?
Companies sometimes offer tools to disable tracking
✕ Remove Ads
If you're concerned about your privacy online, then you're not alone. This isn't a new phenomenon, and countless people within online privacy communities online are also incredibly against tracking. Browsers like Vivaldi are built on the foundation that your data should be private, and other browsers like Firefox are built to allow you to block everything that you need to block online.
With that, plugins like uBlock Origin, Ghostery, and other plugins will block trackers and block the sharing of your information with the sites that you're using. On your smartphone, you can also disable personalized advertisements on your Google account, but some services are starting to require you to pay a fee if you turn off personalized advertising. Google's move towards the Topics API in Chrome shifts the profile building from a server to the client, but it still means that you're being tracked, just in a different way.
✕ Remove Ads
Really, your best bet is to try to keep on top of blocking things as much as you can. With Chrome's switch to Manifest V3, extensions like uBlock are allegedly worse than they once were, but they still get the job done. That, along with blocking advertisements and trackers elsewhere with something like a Raspberry Pi or a NAS can get the job done, too.