Three ways to find a position
A phone does not have a single “location sensor”. It estimates where it is by combining several sources, each with different strengths. The three main ones are satellites, nearby Wi-Fi networks and mobile network towers.
Satellite positioning
Satellite navigation systems, such as the American GPS and similar systems operated by other countries, use a network of satellites that continuously broadcast their position and the time. A phone’s receiver listens to signals from several satellites and measures how long each took to arrive. Since signals travel at a known speed, those delays translate into distances, and with enough satellites the receiver can work out where it must be.
The phone receives signals only. It does not send anything to the satellites, so the satellites do not know who is listening.
Satellite positioning is often the most accurate outdoors, typically within a few metres under good conditions, though the exact figure varies. It is weaker inside buildings, in dense city streets and under heavy cover, because walls block the signal and reflections can confuse the timing. A cold start, with no recent information, can also take longer to find a position.
Wi-Fi positioning
Wi-Fi networks broadcast names and hardware identifiers. Location services maintain large databases linking those identifiers to places, built up from data collected by devices that knew their position at the time. When your phone sees a particular set of nearby networks, it can look up where such a combination has been seen before and estimate its position.
You do not need to join any network for this to work, because the phone is only noting what it can hear. This approach works well indoors and in cities where there are many networks, though accuracy depends on the database and can be poor in places with few networks. If a router is moved, the stored location can become out of date.
Cell-tower positioning
A phone is always in contact with nearby mobile network towers, and the network knows which tower, and often which sector of that tower, a phone is using. This gives a rough position that is usually much less precise than the other methods, from a few hundred metres in dense areas to many kilometres in rural ones. Using signal strength from several towers can improve the estimate.
An important point is that mobile operators have this information as part of running the network, whatever your phone’s location setting says. Turning off location services on the device limits what apps and the operating system can use, but it does not stop the network from knowing which towers you connect to.
Why phones combine them
| Method | Typical strength | Typical weakness |
|---|---|---|
| Satellite | Accurate outdoors | Slow or poor indoors and in dense areas |
| Wi-Fi | Good indoors in built-up areas | Depends on database quality |
| Cell tower | Works almost anywhere with service | Coarse |
Phones fuse these sources with motion sensors such as accelerometers and compass readings. That is why a map can show your position quickly using Wi-Fi and cell data before a satellite fix arrives, then refine it. Bluetooth beacons can add further indoor positioning in places such as shops and airports. Apps do not read these sensors directly. The request goes through the smartphone operating systems, which decide whether to grant it based on the permission you set.
How location histories get stored
Knowing where you are right now is different from keeping a record. Histories can be stored in several places.
- On the device. The operating system may keep a list of frequently visited places or a timeline so it can offer commute estimates and suggestions. Some platforms store this only on the phone, and some let you choose.
- In your account. If you enable a location history or timeline feature, visits may be saved to your cloud account, where you can usually view, edit or delete them. These features are normally optional, and settings and names differ between platforms.
- In apps. A mapping, weather, fitness, ride or social app that you allow to use location may store its own records on its servers, under its own policy.
- In photos. Pictures can carry location details in their metadata, which can be shared when the file is sent.
- With third parties. Some apps include advertising or analytics code that receives location data, and this can reach resellers such as data brokers.
Even coarse location tracking can be revealing once it is kept over time. A series of points over several nights usually points to a home, and a series of weekday points to a workplace.
Reducing what is shared
Most phones let you choose when an app may use location: never, only while the app is open, or always. Many also offer “approximate” location, which gives an app a rough area instead of an exact point. A weather app seldom needs more. Location is one of the app permissions with the clearest trade-off, and a sensible habit is to grant “while using” access, use approximate location where possible and review which apps have “always” access.
Sharing location with friends or family is a separate feature and has its own settings. If you use it, check who can see you, and for how long. Location sharing between people can matter in sensitive situations, such as after a breakup, so it is worth reviewing periodically.
Location services also help in an emergency or if a phone is lost; features that locate a lost phone depend on it. Turning everything off is a choice with real costs, and the practical aim is usually to keep what you value and trim the rest.