5. Apps. The Apple Watch has a brand new interface that displays apps as small, circular icons. The watch uses what Apple calls a "taptic engine" for alerts and app notifications, so it will vibrate or "tap you on the wrist" when they come in. There's a range of on-board apps like calendar, Maps, photos, and music. Users can control music on their iPhone from the watch, and music can also be played directly from the watch, though it's unclear how much storage the watch has. The WatchKit tools will let developers build more apps for the device.
The Apple Watch, clearly, packs a lot of features into a small package. But here are five things it doesn't have:
1. Universal compatibility. Many of the watch's functions, like receiving calls and emails, require it to be paired with an iPhone. As of now the watch will only work with the new iPhone 6 and 6 Plus, as well as the 5, 5C and 5S. There's also no reason to think it will work with Android and Windows phones.
2. A keyboard. To send messages, they must be dictated into the microphone or selected from pre-set responses. This is similar to how smartwatches powered by Google's Android Wear system currently work. Apple says the watch is smart enough to analyze incoming messages and display the appropriate responses that can be sent back.
3. It's own camera. The Watch can display favorite photos from a Mac or iPhone, but it doesn't have its own built in camera. It can be used as a remote viewfinder, however, for the camera on your phone. And you can use the watch to snap the photo or set the timer on the camera's phone.
4. Built-in GPS and Wi-Fi. For that, you need to be connected to your iPhone. If you go out for a bike ride, or do some other activity that can't be measured in steps with the accelerometer, the Watch can't track your distance without your phone.
5. One important thing the Apple Watch doesn't have yet is a firm launch date. Apple said the watch would be available in "early 2015," but it did not clarify beyond that.
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