If you're familiar with the iPhone or iPod touch, chances are you could pick up an iPad and start using it without much trouble. All three devices change picture orientation by simply rotating the device via built-in, three-axis accelerometers. Like the iPhone and iPod touch, iPad has a full QWERTY on-screen keyboard. When the device operates in landscape mode, the iPad's virtual keyboard is almost the same size as keyboards found in iMac systems.
Apple includes a number of basic applications on the iPad, such as its Web browser Safari, its magazine and book app Newsstand, its music store iTunes, and other apps with handy, self-explanatory names: Mail, Photos, Clock, Calendar, Notes, Contacts, Messages, Camera, Game Center. There are more -- far more -- available in the App Store. There are more than 650,000 apps listed in the app store, and more than 225,000 of them are designed specifically for the iPad. Apps designed for the iPhone will still run on the iPad, but they won't look as good on the device's larger screen.
The number of apps available for iOS keeps growing. The mobile operating system continuously changes, too. Apple has kept the same basic look for every version of iOS: Rows of app icons make it simple to access each application. Swiping left or right on the display reveals additional screens of icons, though a dock at the bottom of the screen doesn't change as you swipe between screens (it's there to hold the apps you use the most).
Many other features of iOS have become fairly standard for touch devices. A pinching motion can be used to zoom in and out of photos and web pages. Holding down on apps can be used to delete icons or reorganize them. Dragging app icons on top of one another organizes them into folders. Swiping down from the top of the screen pulls down Apple's Notification Center, a screen that organizes notifications (new e-mail and text messages, alarms, missed calls, and so on).
Games and other apps make use of the iPad's hardware in various ways: Some are controlled by rotating and tilting the device, triggering its motion sensors, while others rely on touch controls like tapping and swiping. The third and fourth generation iPads also support Siri, Apple's "voice assistant" which can be used to control various parts of the device.
Now that we've got a basic grasp of how the iPad works, let's take a look at some of its most common uses. These are the reasons 100 million people have bought iPads to replace (or augment) their laptops and smartphones.