The Apple Watch depends on an iPhone for pretty much everything – and its Bluetooth connection is an umbilical chord for all data, GPS and even Apple Watch apps. However, it's not completely useless if you happen to leave your phone behind.
If you're heading out for a morning jog, want to roam the family estate phone-free, or just forgot your mobile when you headed into the office, you don't have to take your Apple Watch with you.
Essential reading: Ultimate Apple Watch guide for every user
Read on for a full round up of all the things your Apple Watch can do when you leave your iPhone at home.
Track your fitness
All of the Apple Watch's activity tracking features carry on working without a phone around, though you can't sync your statistics back to the Health app or the Web until you've found your iPhone again. The Apple Watch will still tell you to stand up at various intervals, prompt you to meet your running goals, and so on, so you can head out for a run without your iPhone. You can't track GPS location without a mobile, though.
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). 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 Passbook app
At the moment, only Apple-made apps are allowed to run on the Apple Watch itself rather than the iPhone — and that includes Passbook. 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). Note that the Passbook app is getting rebranded as Wallet when iOS 9 arrives in the autumn.
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. When WatchOS 2 arrives you'll get a nice-looking nightstand mode, making 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.
The Apple Watch 2 is set to be even more useful away from an iPhone. Read our full guide to everything we want to see, as well as current users, in our Apple Watch 2 guide.