Thanks, agreeing to be tracked is FAR better than what I was thinking.
Feepmail.
FReepmail. Damn you Otto Kor Wrecked!
Well, if Wi-Fi is on, and/or Bluetooth is on, your phone will periodically send out “beacons” - essentially little “Hey, who’s there?” messages. This typically includes the MAC address of your device - and that MAC address is solely on your device - and no other device. Now, there are ways to spoof or fake that, but their above “basic” level.
If location services is on, any app on your phone that wants to use (or needs to), will use it. Many require it to be on to even start up (Waze, for example, won’t do much with it turned off).
So, basically, when you’re out and about in public, turn off wi-fi, turn off bluetooth, and turn off location services.
Now, I leave bluetooth on, but have my phone paired with my headphones. It’s not going to pair with anything else - because I’ve not asked it to do so. I’m sure there are ways to remotely MAKE it pair, but again, that’s above a basic level.