Apple's Watch is one of the most popular wearables around, and now we have the Watch 2 hitting UK stores, adding loads of cool new features such as water resistance and built-in GPS.
All versions of Apple Watch run something called WatchOS, a nifty bit of software of Apple's own design. But what is WatchOS, how do you update to the latest version and what features does it add to the Watch wearable? Here's all you need to know about WatchOS.
What is WatchOS?
WatchOS is the operating system (OS) that runs on every Apple Watch - basically, the watch equivalent of iOS, which you'll find on iPhones and iPads.
Operating systems essentially sit between the hardware - in this case, the Apple Watch - and the apps that you download. Everything that you do on your Watch is possible because of WatchOS. It's the menus that you scroll through, to load up apps and tweak the Watch's settings. It's the clock faces and other built-in features that you see when you turn your Watch on.
So if it wasn't for WatchOS, your Apple Watch would basically be a pretty piece of heavy, useless jewellry.
What is the latest version of WatchOS?
WatchOS is constantly being improved by Apple, with new versions occasionally rolling out to existing Watch devices.
The latest version of WatchOS is WatchOS 3. This is the version which comes pre-installed on the Watch 2, but older Watch wearables can upgrade to the latest WatchOS 3 via an over-the-air update. See later in this article for full details.
What features does WatchOS 3 add to the Apple Watch?
WatchOS 3 is a big update for the Apple Watch, adding quite a lot of important new features.
For a start, you now get faster access to your most-used Watch apps, via the 'Favourite Apps' feature. No more scrolling for ages to find the one you want. WatchOS 3 also gives you a full, proper iPhone-style Control Center, which allows you to quickly toggle key features like Airplane Mode and Do Not Disturb.
There's also a very cool new SOS feature, which could literally save your life.
And if you're creating your own futuristic connected home, WatchOS 3 will also give you complete control over your supported home tech. Fiddle with your lights, turn off your telly and get some Barry Manilow playing, all from your Apple Watch's dinky screen.
For a full run-down of the best new WatchOS 3 features, check out our complete guide to WatchOS 3.
How do I update my Apple Watch to the lastest version of WatchOS?
If you're using an older version of WatchOS, it's easy enough to download and install the latest update - in this case, WatchOS 3.
First, make sure your iPhone is connected to a WiFi network and then open the Apple Watch app.
In the MyWatch tab, tap on General, and then Software Update. If an update is available, you can tap Download and Install to proceed.
Now just follow the on-screen instructions to complete the update. You'll need to enter your PIN or use TouchID to prove your identity and agree to Apple's usual massive list of terms and conditions, of course. Then the update will download to your iPhone and install on your Watch, providing the two are connected.
When will WatchOS 4 be announced?
We're expecting Apple to reveal some more details of the next version of WatchOS, most likely to be called WatchOS 4, at WWDC 2017. The World Wide Developer's Conference is Apple's annual developer event, which takes place in June in California.
For more info on WWDC 2017, have a gander of our Apple Events Guide.