Smartphones are a window to the world for billions of people around the world, with latest estimates suggesting 45% of the planet now own an internet-enabled handset.
Many young people rarely let their phones out of sight, so the thought of not knowing where your device is for an extended period of time is particularly terrifying.
Fortunately, help could be at hand, but it will require you to have prepared ahead of time, as well as keeping location services turned on. In addition to giving you an idea of where it is, this will also allow you to remotely lock or wipe it.
This does make it dependent on your phone having battery life, so if it runs out of juice you may be out of luck. The first step we'd suggest is backing up all your data, just in case you can't get it back. Here's our guides on how to back up Android and how to back up an iPhone.
Below we'll consider the options built into each major mobile operating system to explain how to track your lost or stolen phone. For each of these you will need to be signed into either your Google or Apple account on the phone before you begin.
Some third-party options are also available. Prey is a particularly popular option, available not only for mobile devices but also Windows, OS X and Ubuntu laptops. If you have several devices spanning multiple platforms, it's worth considering an option such as this that lets you track them all from a single interface. Read up on how to track lost laptops and smartphones with Prey.
How to find a lost Android phone
Find My Device, previously called Device Manager, offers the easiest way to track an Android phone. It's a free download from the Google Play Store, and you can also access the service from any browser by visiting google.com/android/find should your device become lost.
Find My Device offers options to ring, lock or erase your device, should it get out of your hands.
Another option, if your phone is switched off, is to check your location history to find its last reported location. You can do this by visiting myaccount.google.com/activitycontrols and tapping on Manage Activity under Location History.
You'll now see a map of all the places in which your device has reported its location during a time period that you specify. The last known location is where Google last saw it before the battery died, and if your luck's in it may still be there.
Note that location history uses Wi-Fi- and mobile signals rather than GPS, so it won't be as accurate as Android Device Manager.
How to find a lost iPhone
To locate a lost Apple device you need Find My iPhone - but before you lose your iPhone you'll need to ensure it's set up on your device. Just tap on Settings, iCloud, then scroll down to and enable Find My iPhone. Also turn on the option below, which sends your last known location just before your battery dies.
Find My iPhone requires location services to be active, too, which you'll find under Settings, Privacy, Location Services.
Having set up Find My iPhone, you have two ways to track a lost device. Firstly, you can use the free Find My iPhone app on another Apple device to track your phone.
Alternatively, you can sign into your account on a desktop browser at iCloud.com, then tap Find My iPhone.
If you have multiple Apple devices select the one that's been misplaced.
Having selected your phone, Find My iPhone will show you on a map its last known location, and offer options to sound an alarm, lock it or erase its contents.
For a more thorough guide to Find My iPhone see our sister site Macworld: How to use Find My iPhone.
Despite a 2016 patent suggesting Apple was going to add the ability to track location even when the device is switched off, there has been no official line on its inclusion since.