Tracker anti-stalking alerts: what your phone is telling you
Item trackers solved a real problem and created another one. A device that reports its location to a global network, costs very little, and fits inside a coat lining is obviously useful for finding a lost bag - and just as obviously useful for following a person who has not agreed to be followed.
The industry response is a set of features that are worth understanding, because most people first meet them as a confusing notification.
What the alert is
Both Apple's and Google's platforms detect when a tracker that is not registered to you has been moving with you over time, away from its owner. When that pattern is detected, your phone tells you, usually with wording along the lines of an unknown accessory being found moving with you.
This is now a cross-platform standard rather than an Apple or Google feature. iPhones detect Android-network trackers and Android phones detect Apple-network ones, which closed the gap that made early trackers genuinely dangerous.
Trackers separated from their owner also emit a sound on their own after a period, so an unfamiliar tracker will eventually announce itself even to someone without a smartphone.
What to do if you get one
First, check the obvious explanations, because these account for the overwhelming majority of alerts. A borrowed jacket, a shared car, luggage carried by a family member, a rental vehicle with a tracker left in it, a friend's keys in your bag.
If none of those fit, use the alert itself. Tapping it lets you make the tracker play a sound so you can find it, and view identifying information about it. Apple's platform can reveal the last four digits of the owner's phone number when the tracker has been marked lost.
Do not disable it before deciding what you want. If you have any concern for your safety, the recommendation from both platforms and from domestic abuse organisations is the same: leave it active, get somewhere safe, and contact the police, who can use the tracker's serial number to identify the owner. A disabled tracker is evidence you have destroyed.
Why this is good news for ordinary owners
There is a trade-off here that is worth stating plainly. These features mean a tracker is not an anti-theft device. Someone who steals a bag containing a tracker will, before long, be told by their own phone that it is there.
That is a deliberate design decision, and it is the right one. It means trackers are excellent for recovering things you lost - the wallet on the café table, the case at the wrong airport - and poor for recovering things someone took. Since losing is far more common than being robbed, that trade is a good deal, and it is the honest framing behind how Bluetooth trackers work.
If you own trackers, a few courtesies
Register every tracker to your own account, not a shared family one, so alerts resolve cleanly. Tell people if you put a tracker in shared luggage or a car someone else drives - an unexplained alert is alarming and a five-second heads-up prevents it. And if you put one in a child's bag, be aware the parent of their friend may get an alert during a sleepover; the wider question is covered in labelling a child's bag.
The takeaway
A tracker in your wallet is a recovery tool for the thing that actually happens to you. The alerts are the price of that system being safe to have in the world, and they are a price worth paying. What to do in the hour after a wallet genuinely goes missing is in this guide.