The front surface of the Apple iPhone has only one button -- the Home button. Pressing the Home button takes you to the main screen of the iPhone's graphical user interface, where the pre-installed Apple applications are housed when you first get your phone. You simply swipe from right to left or vice versa to change pages and access additional apps. From any screen, you can also choose from the device's four primary functions using icons at the bottom of the screen. By default these are:
- Phone: This app allows you to add contacts, check voice messages and make calls via a host of networks including 3G, GSM or EDGE cellular phone service. Additional network capabilities have also been added to latest phones.
- Mail: The Mail app allows you to send and receive e-mail via POP and IMAP, and includes in-line picture, HTML and push e-mail capabilities. Since iPhone 4S, voice dictation is also included.
- Safari: This is the built-in Web browser that has come with all iPhone OSes.
- Music: Formerly called the iPod app. Despite the name, Music allows you to store and play not only music, but also audiobooks and podcasts from your playlists.
You can swap other applications into these positions by pressing and holding any one of the above until all app icons begin to shake, sliding it onto the main screen and sliding something else into the bottom area in its place.
You can open the iPhone's other applications from the upper portion of the Home screen. These include a calendar, calculator, notepad, and widgets, or mini-applications made specifically for the iPhone. Older iPhones include a 2.0- or 3.2-megapixel camera along with software you can use to organize your pictures -- the iPhone 5s model ups the stakes with an 8-megapixel camera. You can also use an iPhone to check weather reports and stock quotes. Even though the iPhone doesn't support Flash, which YouTube's non-mobile site relies on, you can watch YouTube videos using the corresponding application. An Apple version of YouTube was built in prior to iOS 6. Now the iOS requires that you download either the Google YouTube app or another video search and play app that can access YouTube. The virtual keys and buttons you need to navigate each application appear only when you need them.
The shape of the screen changes when you need it to as well -- you can shift the perspective from vertical to horizontal by tilting the phone. An accelerometer inside the iPhone lets the operating system know to change the orientation of the image on the screen. This means that you can scroll through long lists of music files on a long, narrow screen, and you can watch movies in a widescreen format. You can learn more about accelerometers in How the Wii Works.
Other physical buttons and switches, aside from the Home button, are located around the edge of the phone. An on/off or sleep button is located at the top of the phone. A switch on the left side lets you set your phone from ringing to silent, and just below that are the volume buttons.
The second generation of the iPhone introduced several new features. We'll take a closer look at those in the next section.