The iPhone is a line of Internet and multimedia-enabled smart phones designed and marketed by Apple Inc.
The first iPhone was unveiled on January 9, 2007 and sold on June 29, 2007.
An iPhone can function as a video camera, camera phone with text messaging and visual voicemail, a portable media player, and an Internet client with e-mail, web browsing, and both Wi-Fi and 3G connectivity.
The user interface is built around the device’s multi-touch screen, including a virtual keyboard rather than a physical one.
Third-party as well as Apple applications are available from the App Store.
These apps have diverse functionalities, including games, reference, GPS navigation, social networking, security and advertising for television shows, films, and celebrities.
There are four generations of iPhone models, and they were accompanied by four major releases of iOS.
The original iPhone was a GSM phone that established design precedents like screen size and button placement that have been maintained through all models.
The iPhone 3G added 3G cellular network capabilities and A-GPS location.
The iPhone 3GS added a compass, faster processor, and higher resolution camera, including video.
The iPhone 4 has two cameras for FaceTime video calling and a higher-resolution display.
On January 11, 2011, Apple and Verizon together launched a CDMA2000 compatible iPhone 4 specifically for the Verizon network in the US, released on February 10, 2011.
The back of the original iPhone was made of aluminum with a black plastic accent.
The iPhone 3G and 3GS feature a full plastic back to increase the strength of the GSM signal.
The iPhone 3G was available in an 8 GB black model, or a black or white option for the 16 GB model.
They both are now discontinued.
The iPhone 3GS was available in both colors, regardless of storage capacity.
The white model was discontinued in favor of a black 8 GB low-end model.
The iPhone 4 has an aluminosilicate glass front and back with a stainless steel edge that serves as the antennae.
It is available in black; a white version was announced, but has as of January 2011 not been released.
The touchscreen is a 9 cm (3.5 in) liquid crystal display with scratch-resistant glass.
The capacitive touchscreen is designed for a bare finger, or multiple fingers for multi-touch sensing.
The screens on the first three generations have a resolution of 320 x 480 (HVGA) at 163 ppi, while that of iPhone 4 has a resolution of 640 x 960 at 326 ppi.
The bottom of the iPhone sports a speaker (left) and a microphone (right) flanking the dock connector.
One loudspeaker is located above the screen as an earpiece, and another is located on the left side of the bottom of the unit, opposite a microphone on the bottom-right.
The iPhone 4 includes an additional microphone at the top of the unit for noise cancellation, and switches the placement of the microphone and speaker on the base on the unit—the speaker is on the left.
Volume controls are located on the left side of all iPhone models and as a slider in the iPod application.
While the iPhone is compatible with normal headphones.
Apple provides a headset with additional functionality.
A multipurpose button near the microphone can be used to play or pause music, skip tracks, and answer or end phone calls without touching the iPhone
The iPhone features an internal rechargeable battery.
The iPhone can be charged when connected to a computer for syncing across the included USB to dock connector cable, similar to charging an iPod.
Alternatively, a USB to AC adapter (or “wall charger,” also included) can be connected to the cable to charge directly from an AC outlet.
A number of third-party accessories (car chargers, portable chargers, battery cases, stereo dock chargers, and even solar chargers) are also available.
The original iPhone and iPhone 3G feature a built-in Fixed focus 2.0 megapixel camera located on the back for still digital photos.
It has no optical zoom, flash or autofocus, and does not support video recording
Version 2.0 of iPhone OS introduced the capability to embed location data in the pictures, producing geocoded photographs.
The iPhone 3GS has a 3.2 megapixel camera, manufactured by OmniVision, featuring autofocus, auto white balance, and auto macro (up to 10 cm).
It is also capable of capturing 640×480 (VGA resolution) video at 30 frames per second,[63] although compared to higher-end CCD based video cameras it does exhibit the rolling shutter effect.
The video can then be cropped on the device itself and directly uploaded to YouTube, MobileMe, or other services
The iPhone 4 introduced a 5.0 megapixel camera (2592×1936 pixels), also located on the back, which is equipped with a backside illuminated sensor capable of capturing pictures in low-light conditions, as well as an LED flash capable of staying lit for video recording at 720p resolution, considered high-definition.
The iPhone 4 has a second camera on the front capable of VGA photos and SD video recording.
The iPhone was initially released with two options for internal storage size: 4 GB or 8 GB.
Apple discontinued the 4 GB models.
Apple added a 16 GB model.
The iPhone 3G was available in 16 GB and 8 GB.
The iPhone 3GS came in 16 GB and 32 GB variants and still is available in 8 GB.
The iPhone 4 is available in 16 GB and 32 GB variants.
All data is stored on the internal flash drive; the iPhone does not support expanded storage through a memory card slot, or the SIM card.
GSM Models of the iPhone use a SIM card to identify themselves to the GSM network.
The SIM sits in a tray, which is inserted into a slot at the top of the device.
The SIM tray can be ejected with a paperclip or the “SIM eject tool” (a simple piece of die-cut sheet metal) included with the iPhone 3G and 3GS.
In most countries, the iPhone is usually sold with a SIM lock, which prevents the iPhone from being used on a different mobile network.
The GSM iPhone 4 features a MicroSIM card that is located in a slot on the right side of the device.
The CDMA model of the iPhone, like all CDMA phones, does not use a SIM.
All iPhone models include written documentation, and a dock connector to USB cable.
The original and 3G iPhones also came with a cleaning cloth.
The original iPhone included stereo headset (earbuds and a microphone) and a plastic dock to hold the unit upright while charging and syncing.
The iPhone 3G includes a similar headset plus a SIM eject tool (the original model requires a paperclip).
The iPhone 3GS includes the SIM eject tool and a revised headset, which adds volume buttons (not functional with previous iPhone versions).
The iPhone 3G and 3GS are compatible with the same dock, sold separately, but not the original model’s dock.
All versions include a USB power adapter, or “wall charger,” which allows the iPhone to charge from an AC outlet.
The iPhone 3G and iPhone 3GS sold in North America, Japan, Colombia, Ecuador, or Peru include an ultracompact USB power adapter.