Android Wear 2.0 represented the biggest update to Google's smartwatch OS in its four-year history. The revamped smartwatch OS originally launched on two Wear OS watches back in February of last year, and it spent the rest of 2017 working its way onto a wide range of Wear watches.
Essential reading: Check our best smartwatches roundup
The Wear 2.0 upgrade (and the Wear Oreo update) added a whole host of new features, has an emphasis on custom watch faces, fitness and standalone apps. iPhone users are also in line for a much better iOS/Wear OS experience.
That's a thread that will continue as Android Wear has now been rebranded to Wear OS to make it a little less confusing for iPhone users who wanted to jump into Google's world of smartwatches.
Read on to get up to speed with everything you need to know about Wear OS…
Wear OS: Standalone apps
Standalone apps are the biggest change for the Wear ecosystem to date. You don't need your phone nearby to use apps on your Wear OS device. Using Bluetooth, Wi-Fi or cellular instead of depending on a tethered phone or cloud syncing, your smartwatch now remains much more functional away from your phone.
Most Wi-Fi enabled smartwatches can already connect up to Wi-Fi, but this is a huge deal for Wear OS watch owners who also happen to have iPhones. It means you can now download apps straight to the watch, making up for the previous lack of app support available when paired with Apple's smartphone.
Worried about security with apps running wild on your wrist? While smartphone-paired watches use secure transfer authentication data via the Wearable Data Layer API, apps will make use of 2.0's new input methods – more on those in a bit – for username and password entry.
Which leads us to…
Wear OS: Play Store
As part of the grand untethering of phone and watch, Wear OS now includes a standalone Play Store, meaning you're able to browse and download Wear apps right to your smartwatch.
This also means you don't need to install the apps on your phone – just the watch itself – as Wear OS doesn't require the two to be paired.
Wear OS: Material design
Google's smartphone design language has now made its way onto Wear OS smartwatches. But it's not a simple cut and paste job.
The design has been specifically optimised for Wear watches, redesigning the app launcher and creating something that's more accommodating for round screens. The way you interact with Wear OS has also been changed to fit in with the app launcher. Instead of the usual left and right swipe to find your apps, pushing the side button will display them in a slight arc. You can even put your favourite apps up the top by holding and dragging them.
There is also a new action drawer at the bottom of the display, providing context-specific actions similar to what you'd get on a smartphone.
These new menus and the like are also much easier to control thanks to Wear OS supporting a rotational input. On the LG duo, a moveable watch dial allows you to move up and down menus, zoom in and out and so on, but the new hardware control option doesn't have to be a side scroller; the platform supports any rotational input. Samsung-style rotating bezel anyone?
Wear OS: Watch faces
Wear OS has been playing catch-up with Apple's watchOS in making its watch faces more useful. You are able to view multiple data from different third-party apps on the watch face. Think complications on Apple Watch. In fact, that's exactly what Google is calling the new watch face widgets – complications.
Now users will be able to have data from Spotify and Google Fit, for example, displayed on a single watch face and can also interact with them – devs can supply data to any watch face using the API.
The way you can pick and change watch faces is also much better now. You can simply line up your favourite faces and swipe from the existing watch face to access them. For example, you could have three different faces lined-up, complete with relevant complications, for work, running and home-time and access them with easy swiping.
Wear OS: Android Pay
Like its Apple and Samsung rivals, you simply load up your bank card to the device and tap away to buy that coffee or pretzel (other items are available).
Wear OS: Messaging
Sending messages is limiting on the wrist since the screens are so small, but that should hopefully be alleviated a bit with Wear OS's input methods. A small keyboard can be swiped to let you type out messages, and handwriting recognition will let you draw single letters or join words to send messages.
Google is offering its own native keyboard but is also opening the door for third-party keyboard apps to offer alternatives.
And that's not all. Google is bringing over the smart replies that Gmail users will be familiar with, giving you the option of three possible responses to quickly reply to a contact. These smart replies are generated on the watches themselves, meaning no personal info is shared with Google's servers.
Responding to messages no longer requires swiping to another screen, either, as you are able to tap on the message and view more data before deciding on your next course of action.
Wear OS: Fitness
Slowly but surely, Wear OS is becoming a better place for fitness lovers. Especially with specialist Wear running sports watches such as the Moto 360 Sport, Polar M600, and Nixon's The Mission. And the LG Watch Sport too, of course.
Google has made improvements with Google Fit integration, including the addition of individual activity counting within Fit – think press-up reps and the like.
If you love working out with music, then it's much easier to launch your workout playlist, whether that's from Spotify or another music service, straight from the Wear homescreen. And your phone doesn't even need to be turned on for that, which is definitely very cool.
Talking of music, streaming tunes is now an option. The updated Google Play Music app allows you to stream music not stored on your watch using Wi-Fi or LTE connectivity.
Also, when you work out with a cellular-connected Wear OS device, you can still use the calling and messaging functionality.
This is actually an area Google is looking to double down in, and one of the big takeaways from our chat with Dennis Troper, head of product for Android Wear, is that Google wants Wear OS to be better at proactively coaching and motivating users to be active.
Wear OS: Notifications
Anyone that has used an Android Wear watch will know how those Google notification cards had a habit of obscuring the watch faces and making the place a feel a little cluttered. Now things work a little bit differently.
When you get the cards, the watch face will display smaller icons instead of huge messages that take up space. They are also be more manageable with a progress bar on the bottom display showing you how many cards are left in the stack.
When you raise your watch to activate it, it pulls up the card notification before it hides away again. You are still able to swipe up from the bottom to go through your notifications as normal, but it gives Android Wear a much cleaner look and feel.
The notification cards themselves have been redesigned as well, to show primarily light text on a black background instead of dark text on a white background. According to Google, this should help save battery life and lessen the intrusion of bright notifications.
Expect Google to make some changes to how notifications work moving forward, as the search giant wants to make notifications even more glancable and give you more information more quickly.
Wear OS: Google Assistant
Wear OS also adds Google Assistant to your smartwatch, helping you to find answers using your voice. It's like Alexa but less good. Though Google does want this to be a big point for its smartwatch OS, so expect a smarter Google Assistant moving forward.
You can ask Google Assistant about the weather, get it to set timers or remind you to buy a coffee or a pretzel (other items are available) – you just hold down the standby button on your watch or say "OK Google."
Wear OS: It's not for everyone
Wear OS isn't available for every Wear smartwatch. Older devices such as the original Moto 360 and the LG G Watch miss out. That's not entirely surprising, given that both watches are very long in the tooth now. Google usually stops updating its flagship phones and tablets after a similar time period – and both have been succeeded by multiple sequels.
It's the first notable deviation away from the philosophy of a controlled smartwatch experience for all.
This is the official list of existing devices, most of which should now be running the new software: Asus ZenWatch 2 & 3; Casio Smart Outdoor Watch; Casio PRO TEK Smart; Fossil Q Founder; Fossil Q Marshal; Fossil Q Wander; Fossil Q Control; Fossil Q Venture; Fossil Q Explorist; Huawei Watch 2; LG Watch Sport; LG Watch Style; LG Watch Urbane and 2nd Edition LTE; Michael Kors Access; Moto 360 2nd-gen; Moto 360 Sport; New Balance RunIQ; Nixon's The Mission; Polar M600; Louis Vuitton Tambour; Montblanc Summit; Ticwatch S & E; Misfit Vapor; Movado Connect; Skagen Falster; Tommy Hilfiger 24/7 You; Diesel Full Guard; Guess Connect; Gc Connect; and the Tag Heuer Modular Connected.
Wear OS: New smartwatches
The LG Watch Sport and Watch Style were the first to debut Wear 2.0, and after that we saw a wave of updates, with the very latest arriving branded as Wear OS. Recently, we've seen the debut of the Kate Spade New York Scallop, Tag Heuer Connected Modular 41 and Skagen Falster. In the future, we have the Hublot Big Bang Referee 2018 FIFA World Cup Russia and the Huawei Watch 3. We expect we might see some new watches sporting the Wear OS branding at Google I/O in May too.