Shopping malls track cell phones. You are a dot moving about on a computer screen but when you buy a shirt they have your name and address and what credit card you used.
Next time you enter the mall they know your name and what time you showed up and what stores you looked at and anything you bought. They sell this info to anyone. Store security uses facial recognition.
I remembered years ago a grocery store clerk would greet me by name at the checkout and I asked how they knew. She answered it comes up on the screen. They know all that you buy.
Yahoo and Gmail scan your pc and devices and capture your other email address’s you have. I know as I do not store any at yahoo at my Yahoo account yet they bring up the other address’s I have in my Thunderbird email program on my pc that has a different domain other then yahoo.com. You can have location home address’s in the email address book.
Also the cell phones and smart tv’s and cars listen in. Notice ads appear on the pc or tv about what you are talking about.
There are also GPS tracker apps you can download on your cell phone that will track everywhere you go. Also map software for the car does this.