How the Apple Watch Works

Although the shape and functionality of each Apple Watch will be largely the same, Apple is introducing a choice of sizes, colors and even metal composition, along with a selection of accompanying watchbands -- some utilitarian and some quite posh.

Three models of the Watch itself will be available: Watch, Watch Sport and Watch Edition. Watch is composed of a custom stainless steel alloy, available in polished or space black, and will have a sapphire crystal face. Watch Sport is made of anodized aluminum, available in silver or space gray, with an Ion-X glass face. Watch Edition is composed of 18-karat yellow or rose gold with a sapphire crystal face.

You will also be able to choose from a selection of specially designed straps, depending upon which model you get, including the following:

Each Watch model comes in two sizes and each strap type is available for both sizes.

Not only does this give you a number of style choices, but you can customize what shows on the face, as well. As planned for launch, Watch will let you to choose from 11 different watch-face designs named Chronograph, Color, Modular, Timelapse, Solar, Astronomy, Motion, Utility, Simple, Photo and Mickey Mouse.

Some look like traditional analog watch faces with moving hands and others display various types of digital information. The Astronomy face shows your location on the planet and allows you to pan to the moon or zoom out and see the other planets in our solar system. Solar shows the sun's position in a sort of a sundial arc. Mickey Mouse, as the name suggests, looks like the old-school analog watch that used Mickey's arms for the minute and second hands.

You can also personalize many of the watch-faces in a variety of ways, including changing the colors and rearranging or adding functional items, such as a display of your next scheduled event, the time in another time zone, the weather, the lunar phase or your activity levels.

Read on to find out what makes the Watch tick, so to speak.

The form factor of the watch case is a metal rectangle with rounded edges. All three versions of the watch come in two size choices: 38 millimeters (1.5 inches) or 42 millimeters (1.65 inches) in height. Other measurements have not been disclosed at the time of this writing.

Apple employed metallurgists to make the metal alloys of the watch cases as strong as possible. The anodized aluminum of the Sport model is reportedly 60 percent stronger than traditional aluminum alloys, and the gold of the Edition model is twice as strong as normal gold.

On the right side of the device (if looking at the watch face) is a knob Apple refers to as the Digital Crown. It looks like the crown you would use to wind or set the time on a traditional analog watch, but on Apple Watch, it acts as an input device that allows you to scroll through or zoom into or out of whatever is showing on the screen. You can also press it like a button, which usually takes you to the home screen. How it behaves will depend upon context, but the Digital Crown allows navigation without blocking your view of the screen's content with your fingers.

An oblong button below the crown is used to bring up contacts (called Friends) with a single press, and for using Apple Pay -- Apple's new near field communication (NFC) enabled payment method -- with a double press.

Two small buttons on the back can be used to remove or re-attach the watch bands.

The touchscreen is a flexible Retina display. In the case of Watch and Watch Edition, it's protected by a single crystal of machined, polished sapphire, which is the second hardest transparent material next only to diamond, according to Apple. The Sport model is protected by Apple's custom Ion-X glass, a scratch and impact resistant aluminosilicate glass, strengthened at the molecular level by replacing smaller ions with larger ones. Ion-X stands for "ion exchange."

The display senses touch as you would expect on any touchscreen device, but small electrodes were incorporated which allow it to also sense force (something Apple has dubbed Force Touch). As a result, the touchscreen can distinguish between a press and a tap and act accordingly.

The Watch's sensors include an accelerometer and gyroscope to detect movement. Also, at the back of the watch (the part that touches your wrist), there's a heart rate sensor covered in ceramic and zirconia and made up of photodiodes and infrared and visible-light LEDs that fire through four sapphire lenses.

The Watch is powered by an entire computer system on a single custom chip which Apple has labeled the S1 SiP (System in Package). It's enclosed in resin to protect it from impact, moisture, dust, dirt and wear. According to Apple, their full single-chip computer system is an industry first. Per Tim Cook, it has several hundred components wrapped into it [source: Rose].

Another internal component is something Apple is calling the Taptic Engine, a linear actuator that, along with the speaker driver, produces haptic feedback to give tactile cues when a call or notification comes in or an action is performed.

The device includes WiFi 802.11b/g and Bluetooth 4.0 for communication with iPhone. It also incorporates some form of near field communication (NFC).

The device does not appear to include a camera, but it does have a speaker and microphone.

You charge the Apple Watch with a small metal inductive charging unit that's attracted to the back of the watch via magnets using Apple's MagSafe technology. There are no exposed connectors on the watch or the charger.

There's no word yet from Apple about the specifics of the battery life. Apple CEO Tim Cook stated that users would want to charge them every night like a lot of people do with their phones [source: de Looper].

The Watch relies on your iPhone's GPS to get location information, along with the phone's connection to the Internet through cellular or WiFi for most of its other functions. It can reportedly store and allow independent replay of some of your music so that you can jog to your tunes without your phone, but for the most part, you need to carry your phone to use the Watch.

Apple Watch will work with iPhone 5, 5c, 5s, 6 and 6 Plus or later phones running iOS 8 or later. Apple Watch is synchronized with the Universal Time standard and apparently remains accurate within plus or minus 50 milliseconds, making it a good timepiece, but there are a lot of other cool things that the Watch can do.

The display activates when you raise your wrist. You will initially see your chosen watch face, but if you press the Digital Crown, it will bring up the home screen, where you can get to all your apps.

Apps now appear as clusters of simple, circular icons that you can arrange however you like. The clock that appears in the middle of the home screen will take you back to the watch face. The icons vary slightly in size. You can pan around to find apps by swiping on the touch screen, and you can rotate the crown to zoom in and out, viewing a few apps at a time or all of them at once. If you're zoomed out, the icons are too tiny to pick individually, but you can tap on a portion of the screen to zoom into that particular cluster of apps. You can also press the crown to take you back to the normal sized view with the clock in the center. To launch an app, just tap it.

The Force Touch feature lets the Watch differentiate between a tap and a press, so this opens the door for contextually different responses.

If you want to select or customize your watch face, touch the face with a bit of force (not just a tap). You can then swipe through all your choices and select one. You will also see a Customize virtual button, which allows you to pick different colors or select and modify different functionality choices using the crown or touchscreen.

You can bring up something called Glances by swiping upward on the touchscreen. Glances lets you swipe sideways through easily scannable summary data from apps you use often, such as your next upcoming Calendar event, current weather, traffic, your location, your current music, your fitness dashboard or anything else you choose to include, either built-in or third party.

Swipe downward to get to the Notification Center. Using the Taptic Engine, your Watch will "tap" you gently on the wrist when you get notifications, messages or calls. If your phone's sound is off, you could get notifications via the Watch without alerting those around you. When you get a notification, you can lift your wrist to bring it up on the screen.

The speaker and microphone allow you to place and answer calls, record voice messages and dictate messages. There's even a Walkie Talkie feature for voice-to-voice communication with another Watch user.

You can use Siri via the Watch by pressing and holding the crown, or by holding up the Watch, and saying, "Hey, Siri." You can then use Siri as you normally would, for things like getting directions or movie times and dictating messages.

Apple Watch will reportedly autolock when it's taken off and will require a passcode when it's put back on. It will also require a passcode to make payments with Apple Pay, so that someone can't use it for transactions if they've snatched it off your wrist.

Apple Watch has some interesting features outside of its basic functionality. One that Apple calls Handoff lets you start an action on one device and complete it on another, such as read an e-mail on the Watch and respond on the iPhone, or start typing a message on one and complete it on the other.

Notifications will bring up quick button choices that are relevant in the context of the app. When you get a Calendar invitation, you will have these choices: Accept, Maybe, Decline and Dismiss. When a call comes in, you get the expected decline or accept icons. When you receive text messages, the message will be analyzed to generate something called Smart Replies. For instance, if someone types, "Do you want fish or steak for dinner?," virtual buttons that read "Fish" and "Steak" may appear on the screen, and you can press one to send that reply. An example from the keynote was a message that said, "Are you going with 'Love Shack' or 'Wild Thing'?" The possible response choices that came up were "Love Shack," "Wild Thing" and "Not sure." The choices depend on the content of the previous message. You can also hit a dictation icon to speak a message to send via audio or translate into text. Hit a smiley face icon and choose from hand, heart and face animated emojis. It will even let you modify the emojis via touch before sending.

A feature Apple calls Digital Touch will give you new ways to quickly communicate with friends who also own the Watch. To use it, you press the button below the crown, which brings up your friends, and tap on someone's icon. It will show your friend's picture and name along with tiny phone and message icons. If you tap on the middle of the screen instead of selecting one of those icons, the screen will go black except for a dot near the top. You can then communicate with your chosen friend by tapping the screen (which will cause their watch to tap them) once or a number of times, drawing little sketches with your finger or pressing two fingers to the screen to send a snippet of your heartbeat, which the recipient will feel on their wrist. To change the drawing color, you can tap on the dot to bring up the color picker and select between white, red, pink, orange, green, yellow and blue. You can also exchange audio messages through the Walkie Talkie function.

The Watch can also be used as a remote to control music on your iPhone, Apple TV and iTunes on your computer. You can even use it to see what's on the viewfinder on your iPhone camera and set a timer or hit the shutter button to snap a picture. As mentioned before, you can store music on your watch so that you can listen to it even if you leave your phone at home. You would just need Bluetooth headphones if you didn't want to blast your tunes to the world, since the Watch has no connectors.

You can also access some simple settings to turn Bluetooth or Airplane Mode off or on and set Do Not Disturb. And it allows you to ping your iPhone if you can't find it.

As you might expect from a computer in watch form, the Watch also has some robust Timer, Alarm and Stopwatch apps. But those aren't the only apps you can take advantage of on your Watch.

The apps and their interfaces have been designed to allow for lighter interaction that works better on the smaller screen. Apple developed WatchKit to provide developers with APIs and other tools they need to develop apps for the Watch. Developers can already extend the functionality of their apps to create actionable notifications and Glances on the Watch. Sometime in 2015, Apple will allow third-party developers to create fully native Watch apps.

Several familiar iPhone apps have already been ported to the Apple Watch, including Calendar, Maps, Passbook, Music, Stocks, Weather and Photos.

Maps will open on your current location. You can move around the map via the touchscreen as usual, zoom in and out using the crown and touch the small arrow icon on the lower left of the screen to go back to your current location. If you do a force touch (press) on the screen, it will bring up Search and Contacts buttons that allow you to look for places and get directions. Search allows you to select Dictation or make a selection from Favorites or a list of recent searches. Once you've made a selection, it brings up information about the location and lets you choose walking or driving directions. The Taptic Engine gives you different feedback for each direction (left or right) when it's time for you to make a turn so that you could conceivably follow directions without looking at your watch.

The incorporated NFC will allow you to use the Passbook app not only for using loyalty cards or boarding planes and entering events with stored tickets, but also to store your payment methods and pay for things directly with the Watch at retailers that have touch payment capabilities. You do so by double pressing the button (underneath the crown) and holding the watch up to the retailer's payment reader. For safety, it doesn't store or transmit the actual debit and credit card numbers, but uses a specially created device account number for each card.

The Photos app shows your Favorites as tiny contiguous thumbnails on your Watch screen. You can zoom in using the Digital Crown, pan via the touchscreen or tap to further zoom in and swipe through individual pictures. Any photos that you mark as Favorite on your iPhone or Mac will show up on your Watch by default.

There are also two new health-related apps that use the capabilities of the Watch to help you manage your fitness goals. They're called Activity and Workout.

The Activity app monitors your activity throughout the day using the Watch's accelerometer and gyroscope to measure body movement, the heart rate sensor to gauge workout intensity and your phone's GPS and WiFi to track the distance you've moved. The information is displayed on an easy-to-glance-at graphic consisting of concentric rings labeled Move, Exercise and Stand. The Move ring shows calories burned. Exercise shows minutes of any activity comparable to a brisk walk or more. Stand shows the number of times you've stood up from a sitting position. You can click on each ring to get detailed information. The rings draw themselves throughout the day and close when you reach your goals. The app will even suggest new goals and give you a reminder to get up when you have been sitting too long.

The Workout app enables you pick an exercise from a list (mostly cardio workouts like running, walking or cycling) and set time, distance or calorie goals for that activity. You can see your progress throughout the workout and get a summary at the end. The app will also give you reminders when you've reached certain places in the workout, like the halfway point, and award you with badges for various achievements.

The Activity app works in conjunction with the Fitness app on your iPhone to peruse your activity and workout history. You can even share your activity data with third-party health and fitness apps through the iPhone Health app. The health and fitness capabilities of the Watch could make it a good, albeit expensive, alternative to the cheaper, less functional fitness bands such as the Fitbit and Nike Fuelband.

There are already some notable third-party apps in the works. Twitter will let you view and post tweets. American Airlines will allow you to check in and collect bags. City Mapper will purportedly give you directions for local mass transit and remind you of your stops. Pinterest will let you know when you're near sites you have pinned and give you directions. BMW can show you where you left your car and display your charge level. MLB will show you sports scores. Honeywell will let you remotely control your home thermostat from your Watch. Lutron will allow you to control lighting and "scenes" in your home. Nike can be used to challenge your friends to a run. Starwood Hotels even has an app in development that will let you to check in and unlock your room by waving the Watch instead of using a keycard. And many more apps for the Apple Watch are in the works.

The Apple Watch starting price will be $349 for the base model [source: Apple]. There's no word yet on how much the higher echelon models and luxury watch bands will cost, but there's industry speculation that the Watch Edition 18-karat gold models could be anywhere from $1,200 to $10,000 [sources: Biggs, Murphy, Taylor]. Premium timepieces that aren't mini-computers can be priced in that range or much higher, so those price points are not out of the question. But only Apple knows for sure. Apple Watch will become available in early 2015.

Some smartwatches have already beaten Apple to market. The Samsung Galaxy Gear (which requires a Samsung phone), the Motorola Moto 360 (which requires an Android phone) and the Pebble (which works with iOS and Android phones) seem in some ways comparable to Apple Watch. All require a smartphone with which to communicate, all can get notifications to you and all run a variety of apps. Gear and Moto have heart-rate monitors for fitness tracking and Pebble will keep track of your steps. Google's Android Wear is an operating system for smartwatches that's already been incorporated into the Moto 360, Samsung's Gear Live and the LG G Watch. So far Apple Watch is the only one that integrates NFC, so it will be the only one that allows payments via smartwatch for now.

Smartwatches haven't yet caught on as must-have consumer tech items, though. A survey conducted by Canadian firm RBC Capital Markets reportedly found that only 11 percent of respondents who are planning to purchase iPhone 6 or 6 Plus are also planning to buy an Apple Watch [sources: Booton, Dormehl]. But interest could increase as more and more people get the newer phones and start playing with iOS 8 and some of the apps that would integrate with the Watch. It could also increase as the Watch hits the market if positive reviews follow.

This won't be the first time Apple has ventured into an arena where there appeared to be little interest from anyone other than technology enthusiasts. In the past, they popularized the digital music player with iPod, the smartphone with iPhone and the tablet with iPad. Time will tell if Apple can work the same magic in the smartwatch market.