How a phone knows where it is
A phone does not rely on a single method. Instead, the operating system blends several signals and picks the best estimate for the situation.
Satellite positioning (GPS and similar systems). The phone has a receiver that listens to signals from navigation satellites. By comparing the timing of signals from several satellites, it can calculate its position. This works best outdoors with a clear view of the sky and can be slower or less accurate in dense city streets or inside buildings. Note that the phone is receiving signals, not sending location to the satellites.
Wi-Fi. Phones can detect nearby Wi-Fi networks, even without connecting to them. Large databases map the approximate locations of known network identifiers, so by seeing which networks are nearby and how strong their signals are, the phone can estimate where it is, often well enough for indoor use. This is why turning off GPS alone does not always stop a phone from being located.
Cell towers. The phone connects to nearby towers. The network knows which towers a phone uses, and the phone can estimate its position from them. Accuracy ranges from a rough area in rural regions to something much tighter where towers are dense.
Bluetooth. Bluetooth connections and low-energy beacons can help with positioning in places like shopping centers, airports and stadiums. Beacons placed in a building can signal a phone that it is near a certain spot.
Motion sensors and other inputs. Accelerometers, gyroscopes, barometers and compasses among the device sensors help smooth out the estimate between fixes and detect movement.
IP address. Websites can also guess a rough location, usually a city or region, from your IP address, without any permission prompt. This is typically much less precise than phone-based methods and can be wrong.
Who gets to see it
Location can reach several parties.
- The operating system maker may use location for services such as maps, finding a lost device and improving location databases. Settings control how much is kept and whether history is saved to an account.
- Apps can request location through the operating system, which usually asks for permission. Navigation apps need it. Many others, such as weather, shopping or social apps, ask because it enables features, but sometimes also because it supports advertising or analytics.
- Mobile network operators know which towers your device connects to, regardless of your app settings, and are subject to national rules about how long they keep that information and when it can be disclosed.
- Advertising and data companies may receive location data from apps that include their software. This can feed into the industry discussed in the article on data brokers.
- Other people, when you share location intentionally with family or friends, or when you post photos that carry location in file metadata.
Why location data is sensitive
A single point may seem harmless. A history of points, though, can reveal where someone lives and works, their routines, visits to medical facilities or places of worship, and who they spend time with. Even when a record is labeled with a random identifier instead of a name, regular patterns, such as the place someone sleeps at night, can make it identifiable, an issue explored in the article on data anonymization. Location can also be a safety concern, for instance in situations involving stalking or domestic abuse.
Controls on a phone
Names and menus differ between iPhone and Android and change between versions, so look for equivalents of the following.
- Master location switch. You can turn location services off entirely, though maps and emergency features will be affected. Emergency calling usually can still share location with emergency services in many regions.
- Per-app permissions. Typical choices are Never, Ask next time, While using the app, and Always. “While using” is usually enough. “Always” lets an app collect location in the background and should be reserved for apps that truly need it.
- Precise versus approximate. Many systems let you grant only an approximate area, which is often enough for a weather app.
- One-time permission. You can allow access for a single session.
- Location history or timeline. Some accounts store a record of where you have been. You can often pause it, set it to auto-delete after a period or delete past entries.
- Wi-Fi and Bluetooth scanning. Some phones have separate toggles that allow scanning for location purposes even when those radios are off in the normal sense.
- System services. Settings may list system-level uses such as location-based suggestions or ads. Review them if you prefer less sharing.
- Photo location. Camera apps often can be set not to embed location in photos.
Habits worth considering
Review permissions every few months, remove apps you no longer use, and check which have background access. Be cautious with apps that request location without an obvious reason, and read the sections of their privacy policies about location. Remember that turning off location does not stop your phone from connecting to cell towers or reveal nothing to websites through your IP address. For most people the practical goal is to limit unnecessary collection while keeping the useful features, such as navigation, that really depend on location.