Most likely you are aware of website trackers when you're on the internet. The following article, from Apple, has a story to tell about this, and it's worth a read, I think: https://www.apple.com/privacy/docs/A_Day_in_the_Life_of_Your_Data.pdf
I'm not unduly worried about website trackers, but I do block them when I can. That's one reason I use the Brave Browser (https://brave.com/) when I'm on the internet.
Jim Hamm