What You Need to Know About Apple Watch

— -- It doesn't seem that long ago that Apple CEO Tim Cook first began talking about the game-changing Apple Watch that was to come.

Seven months later, what Cook calls Apple's "most personal" device will be on the wrists of the first buyers today as some will have the opportunity to pick up the hotly anticipated wearables from Apple stores or receive a special delivery at home.

If you're curious but haven't pre-ordered a watch, here's a breakdown of the basics to get you started.

How to Order

Even though the watches are launching today, don't expect to see extra inventory in stores. Those who aren't completely sold on the idea yet or don't know which watch they want can schedule a try-on appointment online and then order a device to be picked up at a later date.

Customers can also play with an Apple Watch display unit that lets them demo the interface. However they won't be able to try one on without meeting with an Apple employee.

Compatibility

The Apple Watch is compatible with the iPhone 6, iPhone 6 Plus, iPhone 5, iPhone 5C and iPhone 5S.

Choices, Choices, Choices

The watch comes in three models: the Apple Watch Sport, Apple Watch and the high-end Apple Watch Edition. Each packs as much as 18 hours of battery life, ensuring the device can stay helpful to its user day and night.

The Apple Watch Sport, which is made of aluminum, starts at $349. The Apple Watch starts at $549 for the smaller version and goes as high as $1,049 depending on the watch band. The larger version starts at $599.

The Apple Watch Edition will begin at $10,000 and will be available in limited quantities, making it the ultimate techie status symbol.

Apps

Ever since the Apple Watch was announced last September, developers have been working to transform their app experiences for the wrist.

The results can be found in the Apple Watch app store launched Thursday with thousands of apps encompassing everything from news, retail, travel health and entertainment.

While you likely won't book a European getaway on the Watch, the small screen is ideal for offering alerts and access to quick information, such as your itinerary or the check-out time at a hotel.

What Makes It Different

Much of the interaction on the watch is driven by notifications. Expect the Apple Watch to keep you on track for your appointments, advise you when you may need an umbrella or show you a text message from a friend.

The wrist is "a very interesting place" because users can glance at it while "you can't glance at a lot of other places on your body," Cook told ABC News' David Muir in an exclusive interview after the watch was announced last year.

"You can measure a lot of things from there and you can just get, honestly, a tidbit today of what all it can do," Cook said. "But I think it's huge."

Navigation

While other wearables focus on a touch screen, Apple is making navigation on the watch head easier by letting users move the digital crown to toggle between apps. (You can of course still use the touch screen on the watch.)