This NBC Tech article shares that most websites actively track users extensively as the visit or shop on e-commerce sites

So how exactly is your data collected, stored, and profited from? And how safe is it? Put down that credit card, because it’s time for a lesson on what happens to your personal information when you shop online.

1. What happens when you browse online? – Yes, even when people don’t enter their personal information to buy something, online shops are collecting information about them. That includes which products they click on, how long they spend looking at that product, which browser and operating system they’re using, and their IP address.

2. What are companies doing with that stuff? – They are using it for their own research. If a sporting goods store, for example, sees you like a certain brand, it might try to show you more of that brand next time you visit. But there is no guarantee that data will stay put.

3. Which companies are getting my data? – It’s not like e-commerce websites are creating reports and sending them off to Google. Instead, companies like Google and Facebook offer free social media and analytics tools. In return, they get access to data.

4. What are these cookie things I have heard about? – Companies build profiles of people using “cookies.” In his paper, Libert compared them to the “tracking bracelets” that scientists place on “migratory birds.”  Wherever your browser goes, this little text file goes too. A website might create one for you. When you come back, it recognizes the cookie and does things like automatically fill out your username and password.

5. What are these companies doing with the data? – Data brokers and ad networks essentially create profiles of you for advertising purposes. It’s supposed to be anonymous. That is not always the case.