Cell phones

Cell phones, including "smart phones", are personal tracking devices.
This was not always the case, and it is not the reason that cell-phones
were originally invented, but that is what they have become.
The NSA, FBI, and police agencies, have all pushed for the development of
generation-four (4G) and generation-five (5G) cell-phone technologies,
which are increasingly good at pin-pointing the location of a cell-phone,
and thus any person who is either talking-on the cell-phone
or has the cell-phone on their person.
Nowadays, the majority of people in the U.S., and in most of the industrialized world,
carry-around these personal tracking devices, and think nothing of it.

In contrast to cell-phones are land-line phones,
which cannot be used to pinpoint a person's location,
although a land-line phone is tied to a specific address and a specific telephone-pole.