The Apple Watch depends on an iPhone for a lot of things, with its Bluetooth connection acting as an umbilical chord for all data, notifications and even Apple Watch apps. However, its smarts aren't completely lost if you happen to leave your phone behind.
And with the Apple Watch Series 2 bringing GPS and waterproofing talents to the wrist party, there's now even more you can do without being tethered to your iPhone.
Essential reading: Ultimate Apple Watch Series 2 guide
Read on for a full round up of all the things your Apple Watch can do when you leave its big brother at home.
Track your fitness
All of the Apple Watch's tracking features carry on working without a phone around, with the Workout app keeping tabs on your, erm, workout, while your goals are monitored through the Activity app.
The Apple Watch will also still tell you to stand up at various intervals, while Series 2 owners can track location on a run through GPS or their activity in the pool.
Take a look at our pick of the best Apple Watch running apps.
Play your tunes
You may well be familiar with using your Apple Watch to control music playback on your iPhone, but there's a limited amount of storage space on the watch itself if you want to go phone-free.
Try it yourself: How to connect Apple Music to Apple Watch
Pick a playlist through the Apple Watch app on your iPhone in advance, and it syncs over. It's not possible to play music through the timepiece's integrated speakers, so you're going to have to connect some Bluetooth headphones too.
Check old messages
New messages won't come through to your Apple Watch without an Apple phone - it has no way of connecting to the Web or a data network — but that doesn't mean all your old messages are lost. The watch caches a number of recent emails, iMessages and SMSs to the wearable device, so if you need to bring up an important tidbit of information then you can do. There's no way of specifying exactly which messages are stored, however.
As long as you've already set up your Apple Pay credentials using an iPhone, you can make actual payments with the Apple Watch on its own. There's a secure token stored on the timepiece itself that proves you are who you say you are, but as a security measure it only works if it's in contact with your skin (take it off and you need to reconnect with your iPhone) and if you have a passcode. For more on Apple Pay, read our complete guide to the technology.
Browse your photos
As with music, there's a small sliver of storage space given over to your photos — if you want to make sure that pictures of your nearest and dearest are with you at all times, then Apple Watch makes it possible. By default, the Favourites album on your iPhone is synced over to the watch, but you can change this through the Apple Watch app on your mobile: creating a dedicated album for timepiece pictures is probably the best option.
Access the Wallet app
Your movie tickets, loyalty cards and money-off vouchers are right there on your wrist when you need them, even if you've accidentally lost your smartphone (or smashed it on the way to the airport). With Apple Pay becoming increasingly prominent, tapping your wrist is a natural alternative to your phone.
Set alarms and timers
All of the usual watch features are still available on the Apple wearable, so your alarm will still go off even if your phone is out of battery or has wandered away during the night. Nightstand mode also makes the Apple Watch even more useful as a miniature alarm clock. Other related functions, such as the watch timer and the stopwatch feature, work fine without a connected iPhone in range.
Tell the time
Good news: the Apple Watch does indeed still function as a watch if you lose your iPhone, so at least you can find out how long it's been since you checked Facebook. It's not just telling the time either — Apple promises that the device keeps time within 50 milliseconds of the definitive global standard. Your only worry then is the battery running out, at which point you'll need to use the position of the sun instead.